CASE REPORT published: 31 March 2021 doi: 10.3389/fimmu.2021.625591 Case Report: Partial Uniparental Disomy Unmasks a Novel Recessive Mutation in the LYST Gene in a Patient With a Severe Phenotype Edited by: of Ché diak-Higashi Syndrome Andrew R. Gennery, Newcastle University, Mireia Boluda-Navarro 1, Mariam Ibáñez 1,2,3,4,5, Alessandro Liquori 1, United Kingdom Clara Franco-Jarava 6,7, Mónica Martı́nez-Gallo 6,7, Héctor Rodrı́guez-Vega 8, Jaijo Teresa 9, Reviewed by: Carmen Carreras 8, Esperanza Such 2,3, Ángel Zúñiga 9, Roger Colobran 6,7,10*† Raz Somech, and José Vicente Cervera 2,9*† Sheba Medical Center, Israel 1 Accredited Research Group in Hematology and Hemotherapy, Instituto de Investigación Sanitaria La Fe, Valencia, Spain, Ekaterini Simoes Goudouris, 2 Department of Hematology, Hospital Universitario y Politécnico La Fe, Barcelona, Spain, 3 Centro de Investigación Federal University of Rio de Janeiro, Brazil Biomédica en Red de Cáncer (CIBERONC), Madrid, Spain, 4 Department of Medicine, University of Valencia, Valencia, Spain, 5 Departamento de Ciencias Biomédicas, Facultad de Ciencias de la Salud, Universidad CEU Cardenal Herrera, Valencia, Khan Saadullah, Kohat University of Science and Spain, 6 Immunology Division, Hospital Universitari Vall d'Hebron (HUVH), Diagnostic Immunology, Vall d’Hebron Research Technology, Pakistan Institute (VHIR), Barcelona, Spain, 7 Department of Cell Biology, Physiology and Immunology, Autonomous University of Barcelona (UAB), Barcelona, Spain, 8 Pediatric Hematology Unit, Hospital Universitario y Politécnico La Fe, Valencia, Spain, *Correspondence: 9 Genetics Unit, Hospital Universitario y Politécnico La Fe, Valencia, Spain, 10 Department of Clinical and Molecular Genetics, Roger Colobran Hospital Universitari Vall d’Hebron (HUVH), Barcelona, Spain rcolobran@vhebron.net José Vicente Cervera cervera_jos@gva.es Ché diak-Higashi syndrome (CHS) is a rare autosomal recessive (AR) immune disorder that † These authors have contributed has usually been associated to missense, nonsense or indels mutations in the LYST gene. equally to this work In this study, we describe for the first time the case of a CHS patient carrying a Specialty section: homozygous mutation in the LYST gene inherited as a result of a partial uniparental This article was submitted to isodisomy (UPiD) of maternal origin. Sanger sequencing of the LYST cDNA and single Primary Immunodeficiencies, a section of the journal nucleotide polymorphism (SNP)-arrays were performed to identify the causative mutation Frontiers in Immunology and to explain the molecular mechanism of inheritance, respectively. Partial-UPiD leads to Received: 03 November 2020 a copy neutral loss of heterozygosity (CN-LOH) of the telomeric region of chromosome 1 Accepted: 16 March 2021 (1q41q44), unmasking the potential effect of the mutation detected. The mutation Published: 31 March 2021 (c.8380dupT) is an insertion located in exon 32 of the LYST gene resulting in a Citation: Boluda-Navarro M, Ibáñez M, premature stop codon and leading to the loss of all the conserved domains at the C- Liquori A, Franco-Jarava C, terminal of the LYST protein. This would account for the severe phenotype observed. We Martı´nez-Gallo M, Rodrı´guez-Vega H, Teresa J, Carreras C, Such E, also reviewed the only two previously reported cases of CHS as a result of a uniparental Zúñiga Á, Colobran R and Cervera JV disomy. In this study, we show that the combination of different strategies, including the (2021) Case Report: Partial use of SNP-arrays, is pivotal to fine-tune the diagnosis of rare AR disorders, such as CHS. Uniparental Disomy Unmasks a Novel Recessive Mutation in the LYST Gene Moreover, this case highlights the relevance of uniparental disomy as a potential in a Patient With a Severe Phenotype mechanism of CHS expression in non-consanguineous families. of Chédiak-Higashi Syndrome. Front. Immunol. 12:625591. Keywords: Chédiak-Higashi syndrome, CHS, primary immunodeficiency, hemophagocytic lymphohistiocytosis, doi: 10.3389/fimmu.2021.625591 LYST, SNP-array, uniparental disomy, loss of heterozygosity Frontiers in Immunology | www.frontiersin.org 1 March 2021 | Volume 12 | Article 625591 Boluda-Navarro et al. Case Report: Uniparenteral Disomy in Chédiak -Higashi Syndrome INTRODUCTION CASE PRESENTATION Uniparental disomy (UPD) is an unusual genetic mechanism in Here we present a 3-year-old girl, born from non- which homologous copies of a specific chromosome are inherited consanguineous parents after a normal pregnancy and cesarean from only one parent (1). This event can occur as hetero- delivery, hospitalized after 2 days of high fever, productive (UPhD) or iso-disomy (UPiD) depending on whether the two cough, clear nasal secretions and lack of appetite. One week chromosomes transmitted are different or identical, respectively before, she had suffered a non-febrile respiratory infection (2). Furthermore, UPiD can be partial (partial-UPiD) when only treated with azithromycin. She presented incomplete ocular a fragment of a chromosome is affected. albinism characterized by absence of pigmentation in the UPD does not always turn out in disease, thus, the clinical peripheral retina but had no history of serious recurrent outcome is directly related to the genetic content, the size of the infections or excessive bleeding. There was no family history of affected chromosomal region, and the degree of mosaicism (3, 4). albinism or hypopigmentation, immunological or hematological On this regard, abnormal phenotypes associated to UPD can alterations, or of deaths at an early age. result from the presence of imprinted genes on the chromosome involved by altering their regulation and dosage due to variations Clinical, Laboratory and Genetic Results in epigenetic marks (5). UPD can also be implicated in During her evaluation, pancytopenia and oculocutaneous autosomal recessive (AR) diseases by uncovering a recessive albinism were identified whilst chest x-rays (CXR) did not disease allele (6–9). show significant alterations. Infectious diseases were ruled out CHS (OMIM #214500) is a rare AR immune disorder by serological screening and direct observation in blood smears. characterized by immunodeficiency and severe Analysis for respiratory viruses was positive for adenovirus and hemophagocytic lymphohistiocytosis caused by altered respiratory syncytial virus (RSV). She showed normal functional cytotoxic lymphocytes, protein missorting in psychomotor development and her vaccination schedule was neutrophil and loss of natural killer (NK) cell function. CHS up to date. Morphological studies were performed both on patients typically present oculocutaneous albinism, thin silvery peripheral blood (PB) and bone marrow (BM) samples. Results white skin, a predisposition to bleeding, neurological dysfunction for PB cells were consistent with CHS alterations. Hypercellular and infections, among others. In a morphological analysis, CHS BM with increased levels of the granulocytic series and lower is detected by the presence of large pathognomonic cytoplasmic erythroid and lymphocytes series was also observed. In PB as in lysosomal vesicles in granulocytic cells resulting from the BM, purple inclusions were detected in both lymphocytes and all dysregulated function of lysosomes (10). CHS immune stages of the granulocytic series. Intense vacuolization, dysfunction is linked to infections and/or lymphoproliferative sometimes with a purple inclusion, was also seen in all cell disorders with a poor prognosis unless treated by allogeneic bone types (Figures 1A–D). BM’s flow cytometry showed a normal marrow transplantation (11). immunophenotype, with an increase of immature myeloid cells CHS is caused by mutations in the lysosome trafficking (Supplementary Table 1). NK cells showed defective granule regulator (LYST) gene, also known as CHS1, which is localized exocytosis with low expression of CD107a on stimulated NK cells on chromosome 1q42.1-q42.2 (12). The LYST gene (Figure 1E) and a slightly reduced cytotoxic capacity (Figure 1F) encompasses 53 exons and encodes for the LYST protein, evaluated by degranulation assay. which contains several highly conserved (BEACH, PH and Differential diagnosis by cytogenetic analysis, including WD40) domains at the C-terminal end. Even though the conventional karyotype by C-banding and FISH revealed a normal exact function of the LYST protein is still debated, the female karyotype (46,XX). Due to the clinical phenotype that combined PH-BEACH motifs are thought to be implicated in included albinism, together with the defective degranulation assay different aspects of vesicular trafficking and, thus, likely playing and the presence of cytoplasmic lysosomal vesicles in granulocytic a crucial role in regulating lysosome-related organelle size, cells, we amplified by PCR the entire patient’s cDNA sequence of fission and secretion (12–14). Both homozygous and LYST gene (53 exons) in 5 overlapping fragments (Supplementary compound heterozygous mutations in LYST gene have been Table 2, Supplementary Figure 1A). PCR products were then previously described in CHS (10). Loss-of-function mutations sequenced by Sanger. The genotype analysis of the patient are associated with the severe CHS childhood form leading to revealed a homozygous frameshift c.8380dupT (NM_000081.3) death if untreated. In contrast, missense mutations are observed variant in the exon 32 (Figure 1G) that would lead to a in patients with a milder form of the disease, allowing survival premature stop codon (PTC) (NP_000072.2: p.Tyr2794Leufs*8). into adulthood (11). The presence of this variant was then confirmed by the targeted Here, we report the first case of CHS resulted from a partial- sequencing of the corresponding genomic region (gDNA). The UPiD in a young patient harboring a novel mutation in the LYST LYST c.8380dupT variant was not reported in the literature or in gene. The mutation was present in homozygosis despite segregation the main population databases (e.g. dbSNP, ExAC and gnomAD). analysis revealed the mother as the only carrier. Subsequent single The effect of the variant on the encoded protein was assessed by nucleotide polymorphism (SNP)-arrays analysis allowed us to identifying and comparing conserved domains in both the reference identify a segmental isodisomy of maternal origin as the cause of and the resulting mutated LYST protein with the NCBI Conserved this uncommon genetic inheritance. Domain Search Tool (https://www.ncbi.nlm.nih.gov/Structure/cdd/ Frontiers in Immunology | www.frontiersin.org 2 March 2021 | Volume 12 | Article 625591 Boluda-Navarro et al. Case Report: Uniparenteral Disomy in Chédiak -Higashi Syndrome FIGURE 1 | Morphological, cellular and molecular findings in the CHS patient. (A–C) Wright stains of peripheral smear showing a neutrophil, lymphocyte and eosinophil with giant intracytoplasmic granules. (D) Bone marrow aspirate. Intense vacuolization and purple inclusions are also observed in immature cells of the myeloid linage. PB: peripheral blood; BM: bone marrow. (E) Degranulation assay was decreased compared to the healthy control both with PHA and PHA + IL2. PBMCs were incubated with or without (resting cells) PHA either alone or with IL-2 for 4 hr at 37°C. Thereafter, cells were stained with fluorochrome-conjugated anti- CD56, and anti-CD107a mAbs. CD107a surface expression was gated on CD56 cells. (F) A flow cytometry-based NK cytotoxicity assay was performed by measuring cytotoxicity against K562 cell line in a 4-hour staining with propidium iodide. The shaded area indicates normal ranges of cytotoxicity tested in healthy individuals. The patient showed a cytotoxic function on the lower range of normality. (G) Family tree and sequence analysis of the patient and his parents. Sequence patterns showing the patient’s mutation c.8380dupT in homozygosis, the normal sequence of the non-carrier father and the mother’s sequence showing the mutation in heterozygosis. Frontiers in Immunology | www.frontiersin.org 3 March 2021 | Volume 12 | Article 625591 Boluda-Navarro et al. Case Report: Uniparenteral Disomy in Chédiak -Higashi Syndrome wrpsb.cgi) (Figure 2). This tool revealed that the variant identified (Affymetrix) for both the patient and her parents. Filters applied might remove all conserved domains responsible for the protein for the detection of CNV were ≥ 20 consecutive markers in a function (PH, BEACH and WD40). Given the analysis performed region of at least 50kb, and for regions of CN-LOH, ≥ 100 markers on the variant effect and the patient phenotype, we have classified in at least 5,000kb. Whilst no CNVs were observed in the parents’ this variant as pathogenic (PVS1 according to the American College DNA, a CN-LOH on the telomeric region of the long arm of of Medical Genetics and Genomics recommendation) (16). Written chromosome 1 encompassing 25Mb (1q41q44) was detected in informed consent from the parents was provided for all genetic the child, accounting for the candidate variant in homozygosis in studies reported here. the LYST gene (Figure 2). A time-line summary of genetic To determine the inheritance pattern, segregation analysis was investigations is represented in Supplementary Figure 2. performed revealing only the mother as the single carrier of this In addition, UPiD can alter the dosage of imprinted genes variant, whereas the father was wild-type (Figure 1C). Bearing in contributing to the phenotype of the disease (5, 17). Therefore, mind the non-consanguinity of the parents, paternity tests to although the truncated LYST protein derived from the confirm family relationships were carried out. Given that CHS is c.8380dupT variant would explain the severe phenotype in our an AR disorder, we conducted a SNP-array (Cytoscan HD, patient, the possibility of an altered imprinted gene dosage as a Affymetrix) according to manufacturer’s protocol (Affymetrix consequence of the partial UPiD was also examined. We Santa Clara, C.A., U.S.A.). The chromosomal region containing consulted the “Geneimprint” portal (http://www.geneimprint. the LYST gene was assessed for copy number variations (CNVs) com/site/genes-by-species) and found that OBSCN and and CN-LOH using Chromosome Analysis Suite software OR11L1 genes, in the region affected by the partial-UPiD, were FIGURE 2 | Schematic representation of the triggering molecular mechanism of CHS in our patient. From top to bottom: the CN-LOH detected by SNP-array (Cytoscan HD, Affymetrix) in chromosome 1 (1q41q44) is delineated as a purple rectangle, the dots depict the altered markers in the array and the green and grey bands represent the 93 OMIM genes affected, including the LYST gene. Below, the LYST gene (NG_007397.1) that encodes for the entire functional protein is depicted. The c.8380dupT (NM_000081.3) frameshift mutation is localized in the exon 32. A lollipop-like (15) image reflects the resulting truncated protein owing to a PTC at 2,800 amino acid that would remove all conserved domains (PH, BEACH and WD40). Frontiers in Immunology | www.frontiersin.org 4 March 2021 | Volume 12 | Article 625591 Boluda-Navarro et al. Case Report: Uniparenteral Disomy in Chédiak -Higashi Syndrome predicted as paternally imprinted. However, the alteration of variant (NM_000081.3:c.8380dupT) in homozygosis in the such genes cannot be related to the CHS patient phenotype. LYST gene. To date, 72 mutations in this gene have been The patient experienced a spontaneous recovery from the associated with CHS (20), and UPD has been reported as the cytopenias. However, she was repeatedly admitted to the hospital causative mechanism only in three CHS cases (including the due to frequent episodes of high fever, general condition patient described here) (17, 21). A comparison of the three cases impairment, and splenomegaly varying between 5 and 15 cm. of UPD in CHS is shown in Table 2. In addition, 11 cases of Recurrence of exacerbated cytopenias required a transfusion of primary immunodeficiencies caused by UPD have been reported red blood cells in one occasion and G-CSF in two episodes. to date (9) (considering this study) but only SCID (22) and LCK Although the patient did not meet the criteria for massive (23) in chromosome 1. Taken together, these data highlight the hemophagocytic lymphohistiocytosis (HLH) established by the rarity of this event. 2004 Hystiocyte Society guidelines the last time she was To assess the pathogenicity of the c.8380dupT variant and its hospitalized (Table 1), given the progression of the condition association to the clinical phenotype of the patient, an in silico and clinical deterioration, she was treated with Dexamethasone analysis was performed, suggesting that the LYST protein might and Etoposide according to the HLH protocol - 94/2004 (18, 19) be affected. The frameshift produced by the c.8380dupT leads to to which she showed good response. Once remission was a PTC in exon 32 resulting in the loss of PH, BEACH and WD40 achieved, the patient received a stem cell transplant (HCT) highly conserved domains at the C-terminal end of the protein. from an unrelated HLA 10/10 compatible donor at 51/2 years Both WD40 and PH domains are involved in targeting proteins after following a conditioning regimen with busulfan, to appropriate subcellular compartments; PH domain also fludarabine and ATG. After 2 years since the transplant, the participates in the protein-protein interaction with a binding patient maintains complete donor chimerism, showing a normal partner. Therefore, the LYST protein would be truncated and physical and neurological development, and has not required non-functional (13). PTC could also initiate an mRNA subsequent admissions into the hospital. degradation by the nonsense mediated decay (NMD), preventing its translation into the protein (24). However, the patient’s LYST RNA was successfully retro-transcribed into DISCUSSION cDNA for molecular studies, suggesting that this transcript would escape the NMD surveillance mechanism. Additionally, This study reports the first case of CHS as a result of partial- we also amplified and sequenced the mother’s LYST cDNA UPiD. The patient harbored a novel pathogenic frameshift region including the c.8380dupT mutation. The similar TABLE 1 | Patient’s clinical and treatment progression from the first admission to date. Reason for Fever. Oral Acute EBV infection.Peritonsillar High fever High fever 48h. Vomiting. Fever 48 h.HSM admission antibiotic rejection. tonsillitis.Vomiting. phlegmon. 72h increase.Food rejection. Clinical laboratory Leucocytes 2,930 1,830 6,460 3,740 3,070 7,030 (cell/mm3) Neutrophils 0 530 710 480 390 2,150 (cell/mm3) Hb (gr/dl) 9.7 9.7 8.4 9.7 6.6 10.6 Platelets (cell/ 82,000 130,000 149,000 69,000 65,000 170,000 mm3) Fibrinogen NA 391 355 407 413 227 (mg/dl) Ferritin (ng/ NA 413 271 316 283 601 mL) GOT (U/L) 59 39 35 218 22 NA GPT (U/L) 43 NA 19 226 19 NA LDH (U/L) 815 414 333 670 410 363 Triglycerides NA 68 259 304 246 NA (mg/dl) Treatment Amox-clav Amox-clav Cefotaxime + Clindamycin Cefotaxime Cefotaxime + Amikacin IVIg G- Dexamethasone Prednisone Acyclovir IVIg G-CSF IVIg CSF Dexamethasone Etoposide* IVIg Others Positive PCR for EBV load: 2141 copies/mL Blood culture: Staphylococci adenovirus ad RSV hominis Age 2 years 3 months 3 years 11 months 4 years 8 months 5 years 1 5 years 2 months 5 years 3 months months NA, Not available; Amox-clav, amoxicillin and clavulanate potassium; PCR, Polymerase Chain Reaction; RSV, Respiratory Syncytial Virus; IVIg, intravenous immunoglobulins; G-CSF, Granulocyte stimulating factor; EBV, Epstein-Barr virus. *First dosage at first admission. Five subsequent administered at the ambulatory. Frontiers in Immunology | www.frontiersin.org 5 March 2021 | Volume 12 | Article 625591 Boluda-Navarro et al. Case Report: Uniparenteral Disomy in Chédiak -Higashi Syndrome intensity of both alleles in the mother’s Sanger sequencing and would explain the severe CHS phenotype and childhood electropherogram rules out a significant degradation of the onset observed in our patient. In addition, although the mutated allele (Supplementary Figure 1B). Therefore, all these genotype-phenotype correlation in CHS cases remains data point out that the LYST c.8380dupT variant is pathogenic controversial, several studies have reported patients harboring TABLE 2 | Summary of reported cases of UPD in CHS with clinical and diagnostic tools detailed. Patient 1 (17) Patient 2 (21) Patient 31 Gender Male Male Female Age at diagnosis 5 months old 6 years old 2 years old Severity Severe Severe Severe Type of UPD paternal UPhD maternal UPiD maternal partial-UPiD Mutation Coding nonsense nonsense frameshift (NM_000081.3) impact HGVS c.11002G>T c.2621_2622delTTinsAA c.8380dupT coding HGVS p.E3668* p.F874* p.Y2794Lfs*8 protein Domains WD40 PH, BEACH and WD40 PH, BEACH and WD40 affected Zygosity homozygous homozygous homozygous Exon 50 6 32 Consanguinity family No No No Clinical features Onset: eczema due to MRSA At diagnosis: oculocutaneous Onset: adenovirus and RSV respiratory infections. infection. albinism, accelerated phase At diagnosis: oculocutaneous albinism, accelerated phase At diagnosis: oculocutaneous albinism, accelerated phase Physical development Delay in the acquisition of motor skills Normal Normal Neurocognitive Delay (Denver Developmental Normal Normal development Screening Test II) a a Morphology Giant granulations in leukocytes Giant granulations in leukocytes Giant granulations in leukocytes. Intense vacuolization and purple inclusion b Hemogram alterations NA NA Hemoglobin: 9.7 g/dL. Leucocytes: 2.93x103/µl – 0% neutrophils, 65.9% lymphocytes, 26.6% monocytes, 7.5% basophils. Platelets: 82x103/µl Blood biochemical Hypothyroidism (TSH 11.3 mU/L, T4 NA High CRP (48.9 mg/L), AST (59 U/L), ALT (43 U/L) and LDH alterations 9.9 mcg/dl, negative thyroid (815 U/L). antibodies. Immunophenotype NA NA Available2 analysis Cytotoxic capacity Absent NK and CTL function. NA Low NK and CTL function. Diagnostic LOH CGH, whole genome SNP-array and SNP markers (1q42–q43 region) SNP-array tools examination q-PCR. Molecular DNA sequencing of LYST exons and cDNA amplification, sequencing of cDNA amplification and sequencing results flanking introns abnormal transcript and PTT analysis 1 Patient reported in this study. 2 See Supplementary Table 1. a Examined in PB. b Examined in PB and BM. UPD, uniparental disomy; UPhD, uniparental heterodisomy; UPiD, uniparental isodisomy. HGVS, Human Genome Variation Society; MRSA, methicillin-resistant Staphylococcus aeureus; RSV, respiratory syncytial virus; NA, not available; TSH, thyroid-stimulating hormone; CRP, C-reactive protein; NK, natural killer; CTL, cytolytic T-lymphocyte; AST, aspartate transaminase; ALT, alanine aminotransferase; LDH, lactate dehydrogenase; LOH, loss of heterozygosity; CGH, comparative genomic hybridization; SNP, single nucleotide polymorphism; PTT, protein truncation test. Frontiers in Immunology | www.frontiersin.org 6 March 2021 | Volume 12 | Article 625591 Boluda-Navarro et al. Case Report: Uniparenteral Disomy in Chédiak -Higashi Syndrome frameshift, nonsense and splice-site mutations resulting in an HLH is a main characteristic of the ‘accelerated phase’ of the absent LYST protein and similar clinical outcomes to that of our disease, hence, being particularly useful when determining the patient (10, 11). In contrast, the milder adult form of CHS is need for a HCT. A decrease in NK-cell and cytotoxic T often due to missense mutation encoding for a partially lymphocytes capacity provides a diagnostic criteria and functioning protein. However, Sá n chez-Guiu et al. (25) predictor of the severity and transformation to HLH (36). In demonstrated different outcomes due to a direct consequence addition to function impairment in NK cells, our patient of changes in protein structure and, especially, in the case of displayed a clinical deterioration with consecutives missense mutations, in electrostatic surface potential (25). hospitalization matching HLH-94/2004 guidelines. Therefore, Therefore, identifying the real molecular effect of the mutation since transplantation appears to be most successful if is crucial to solve genotype-phenotype relationship. performed prior to the onset of HLH or during remission, we Nevertheless, the detection of the c.8380dupT variant in decided to perform HCT once remission was achieved. Although homozygosity, the non-consanguinity of the parents and the a HCT does not prevent the possible neurologic detriment, our results of segregation studies, showing the mother as the only patient remains healthy after two years from the HCT, showing a heterozygous carrier, led us to consider the presence of other normal immunologic, hematologic and neurological development. underlying genetic events, such as chromosomal deletion or loss In summary, we report the first CHS case with a pathogenic of heterozygosity. Consequently, to determine the causative variant in homozygosis as a consequence of partial-UPiD. Risk of molecular mechanism of the disease, a SNP-array was AR conditions, such as CHS, are easily estimated with siblings performed. This analysis revealed that the patient harbored a having a 25% risk of developing the disease. However, the CN-LOH affecting the 1q42.12 – 1q44 region, which suggests a prevalence of germline UPD is harder to quantify with partial-UPiD of maternal origin. In CHS, UPiD owing to CN- frequencies from 0.03 – 0.3% (37–40), being partial-UPiD LOH has been previously identified (21), however, to our significantly lower (40). Despite the low risk of knowledge, this is the first CHS case reported as a consequence recurrence, having detected the heterozygosis c.8380dupT of partial-UPiD (17, 21). The two previously reported CHS variant in the mother of this child and defined the inheritance patients have a severe phenotype at early stages caused by mechanism, will allow a more accurate genetic counseling for nonsense mutations. Manoli et al. (17) reported a paternal future pregnancies and other family members at risk. Taken UPhD proband with additional developmental delays despite together, in non-consanguineous families, UPD should be carrying the most distal mutation among the three cases (Table considered as a potential mechanism of CHS when a 2). The authors argued that this could be the result of additional homozygous mutation is identified. This case also underlines non-detectable effects linked to a deregulation in genomic the pivotal role of SNP-array as a diagnostic approach to assess imprinting of chromosome 1 as previously suggested (26). the molecular mechanism responsible of AR disorders, such Nonetheless, several AR disorders, including the other CHS as CHS. case of maternal UPiD, have been purely described as a consequence of UPD of chromosome 1 without any atypical phenotype, suggesting the lack of imprinted genes on either the paternal or maternal alleles (21, 27). In our case, although DATA AVAILABILITY STATEMENT partial-UPiD encompassed 93 OMIM genes besides LYST, of The raw data supporting the conclusions of this article will be which OBSCN and OR11L1 (http://www.geneimprint.com/site/ made available by the authors, without undue reservation. genes-by-species) were predicted to be paternal imprinted genes, only OBSCN has been related to an AR disorder (i.e. fibromuscular dysplasia and Limb-Girdle muscular dystrophy) (28). Since our patient exhibited no other uncommon conditions ETHICS STATEMENT other than classic CHS, we concluded that the alteration of such The studies involving human participants were reviewed and genes is not related to the patient phenotype. approved by Comité de É tica de la Investigació n con Although there is no clear explanation for the mechanism medicamentos del Hospital Universitario y Polité cnico la Fe. that leads to partial-UPiD observed in our patient, this could be Written informed consent to participate in this study was produced by an early mitotic division error resulting in the loss provided by the participants’ legal guardian/next of kin. of the paternal chromosome 1 segment, as indicated in previous reports (3, 29). In other AR diseases (30–32), partial-UPiD has been associated with mosaicism as a very rare event (33). However, the SNP-arrays technology analyses may have AUTHOR CONTRIBUTIONS disregarded the presence of mosaicism in our patient, especially if we consider that the sensitivity of this technique is MB-N analyzed molecular studies and wrote the paper. MI and 10%, as well as the premature alteration in mitotic division (34). AL supervised experimental findings. CF-J and MM-G On the other hand, CHS is also associated with the performed and analyzed the functional assays research and development of HLH, which affects more than 75% of CHS data analysis. HR-V, JT and CC were involved in the patients within their first decade and it is fatal unless treated (35). management of the patient. ES performed cytogenetic analysis. Frontiers in Immunology | www.frontiersin.org 7 March 2021 | Volume 12 | Article 625591 Boluda-Navarro et al. Case Report: Uniparenteral Disomy in Chédiak -Higashi Syndrome Á Z supervised clinical and experimental findings. RC performed Española Contra El Cáncer” and the “Fundació n Española de and analyzed the molecular studies. JC and RC were responsible Hematologı́a y Hemoterapia”, respectively. for the conception of the study and final approval of the draft. All authors contributed to the article and approved the submitted version. ACKNOWLEDGMENTS We would like to thank “Biobank La Fe” for their useful help in sample processing and supply. FUNDING This study was supported by research funding from FEDER funds (CIBERONC, CB16/12/00284), Instituto de Salud Carlos III grants SUPPLEMENTARY MATERIAL PI16/01113, PI17/00660, PI18/1472, PI19/00812 cofinanced by the European Regional Development Fund (ERDF); as well as from the The Supplementary Material for this article can be found online “Conselleria de Educació n, Cultura y Deporte” GV/2019/084. MB- at: https://www.frontiersin.org/articles/10.3389/fimmu.2021. N and AL are recipients of a fellowship from the “Asociació n 625591/full#supplementary-material 14. Durchfort N, Verhoef S, Vaughn MB, Shrestha R, Adam D, Kaplan J, et al. The REFERENCES Enlarged Lysosomes in beigej Cells Result From Decreased Lysosome Fission 1. Engel E. A new genetic concept: Uniparental disomy and its potential effect, and Not Increased Lysosome Fusion. Traffic (2012) 13:108–19. doi: 10.1111/ isodisomy. Am J Med Genet (1980) 6:137–43. doi: 10.1002/ajmg.1320060207 j.1600-0854.2011.01300.x 2. Makishima H, Maciejewski JP. Pathogenesis and consequences of uniparental 15. Jay JJ, Brouwer C. Lollipops in the Clinic: Information Dense Mutation Plots disomy in cancer. Clin Cancer Res (2011) 17:3913–23. doi: 10.1158/1078- for Precision Medicine. PloS One (2016) 11:e0160519. doi: 10.1371/ 0432.CCR-10-2900 journal.pone.0160519 3. Lapunzina P, Monk D. The consequences of uniparental disomy and copy 16. Richards S, Aziz N, Bale S, Bick D, Das S, Gastier-Foster J, et al. Standards and number neutral loss-of-heterozygosity during human development and guidelines for the interpretation of sequence variants: A joint consensus cancer. Biol Cell (2011) 103:303–17. doi: 10.1042/bc20110013 recommendation of the American College of Medical Genetics and 4. Gaudio Dd, Shinawi M, Astbury C, MK T, KL D, Raca G. Diagnostic testing Genomics and the Association for Molecular Pathology. Genet Med (2015) for uniparental disomy: a points to consider statement from the American 17:405–24. doi: 10.1038/gim.2015.30 College of Medical Genetics and Genomics (ACMG). Genet Med (2020) 17. Manoli I, Golas G, Westbroek W, Vilboux T, Markello TC, Introne W, et al. 2020:1–9. doi: 10.1038/s41436-020-0782-9 Chediak-Higashi syndrome with early developmental delay resulting from 5. Monk D, Mackay DJG, Eggermann T, Maher ER, Riccio A. Genomic paternal heterodisomy of chromosome. Am J Med Genet Part A (2010) imprinting disorders: lessons on how genome, epigenome and 152:1474–83. doi: 10.1002/ajmg.a.33389 environment interact. Nat Rev Genet (2019) 20:235–48. doi: 10.1038/ 18. Bergsten E, Horne AC, Aricó M, Astigarraga I, Egeler RM, Filipovich AH, s41576-018-0092-0 et al. Confirmed efficacy of etoposide and dexamethasone in HLH treatment: 6. Gelb BD, Willner JP, Dunn TM, Kardon NB, Verloes A, Poncin J, et al. Long-Term results of the cooperative HLH-2004 study. Blood (2017) Paternal uniparental disomy for chromosome 1 revealed by molecular 130:2728–38. doi: 10.1182/blood-2017-06-788349 analysis of a patient with pycnodysostosis. Am J Hum Genet (1998) 62:848– 19. Henter JI, Samuelsson-Horne AC, Aricò M, Maarten Egeler R, Elinder G, 54. doi: 10.1086/301795 Filipovich AH, et al. Treatment of hemophagocytic lymphohistiocytosis with 7. Travaglini L, Aiello C, Alesi V, Loddo S, Novelli A, Tozzi G, et al. Uniparental HLH-94 immunochemotherapy and bone marrow transplantation. Blood disomy of chromosome 1 unmasks recessive mutations of PPT1 in a boy with (2002) 100:2367–73. doi: 10.1182/blood-2002-01-0172 neuronal ceroid lipofuscinosis type 1. Brain Dev (2017) 39:182–3. 20. Landrum MJ, Lee JM, Benson M, Brown GR, Chao C, Chitipiralla S, et al. doi: 10.1016/j.braindev.2016.08.010 ClinVar: improving access to variant interpretations and supporting evidence. 8. Mannurita SC, Vignoli M, Bianchi L, Kondi A, Gerloni V, Breda L, et al. Nucleic Acids Res (2018) 46:D1062–7. doi: 10.1093/nar/gkx1153 CACP syndrome: Identification of five novel mutations and of the first case of 21. Dufourcq-Lagelouse R, Lambert N, Duval M, Viot G, Vilmer E, Fischer A, UPD in the largest European cohort. Eur J Hum Genet (2014) 22:197–201. et al. Chediak-Higashi syndrome associated with maternal uniparental doi: 10.1038/ejhg.2013.123 isodisomy of chromosome 1. Eur J Hum Genet (1999) 7:633–7. 9. Soler-Palacı́n P, Garcia-Prat M, Martı́n-Nalda A, Franco-Jarava C, Rivière JG, doi: 10.1038/sj.ejhg.5200355 Plaja A, et al. LRBA deficiency in a patient with a novel homozygous mutation 22. Roberts JL, Buckley RH, Luoc B, Pei J, Lapidus A, Peri S, et al. CD45-deficient due to chromosome 4 segmental uniparental isodisomy. Front Immunol severe combined immunodeficiency caused by uniparental disomy. Proc Natl (2018) 9:2397. doi: 10.3389/fimmu.2018.02397 Acad Sci USA (2012) 109:10456–61. doi: 10.1073/pnas.1202249109 10. Zarzour W, Kleta R, Frangoul H, Suwannarat P, Jeong A, Kim SY, et al. Two 23. Hauck F, Randriamampita C, Martin E, Gerart S, Lambert N, Lim A, et al. novel CHS1 (LYST) mutations: Clinical correlations in an infant with Primary T-cell immunodeficiency with immunodysregulation caused by Chediak–Higashi syndrome. Mol Genet Metab (2005) 85:125–32. autosomal recessive LCK deficiency. J Allergy Clin Immunol (2012) 130 doi: 10.1016/J.YMGME.2005.02.011 (5):1144–52. doi: 10.1016/j.jaci.2012.07.029 11. Karim MA, Suzuki K, Fukai K, Oh J, Nagle DL, Moore KJ, et al. Apparent 24. Gudipati RK, Xu Z, Lebreton A, Sé raphin B, Steinmetz LM, Jacquier A, et al. genotype-phenotype correlation in childhood, adolescent, and adult Chediak- Extensive degradation of RNA precursors by the exosome in wild-type cells. Higashi syndrome. Am J Med Genet (2002) 108:16–22. doi: 10.1002/ Mol Cell (2012) 48:409–21. doi: 10.1016/j.molcel.2012.08.018 ajmg.10184 25. Sá nchez-Guiu I, Antó n AI, Garcı́a-Barberá N, Navarro-Ferná ndez J, Martı́nez 12. Nagle DL, Karim MA, Woolf EA, Holmgren L, Bork P, Misumi DJ, et al. C, Fuster JL, et al. Chediak-Higashi syndrome: description of two novel Identification and mutation analysis of the complete gene for Chediak– homozygous missense mutations causing divergent clinical phenotype. Eur J Higashi syndrome. Nat Genet (1996) 14:307–11. doi: 10.1038/ng1196-307 Haematol (2014) 92:49–58. doi: 10.1111/ejh.12203 13. Cullinane AR, Schäffer AA, Huizing M. The BEACH Is Hot: A LYST of 26. Wassink TH, Losh M, Frantz RS, Vieland VJ, Goedken R, Piven J, et al. A case Emerging Roles for BEACH-Domain Containing Proteins in Human Disease. of autism and uniparental disomy of chromosome 1. Hum Genet (2005) Traffic (2013) 14:749–66. doi: 10.1111/tra.12069 117:200–6. doi: 10.1007/s00439-005-1257-4 Frontiers in Immunology | www.frontiersin.org 8 March 2021 | Volume 12 | Article 625591 Boluda-Navarro et al. Case Report: Uniparenteral Disomy in Chédiak -Higashi Syndrome 27. Turner CLS, Bunyan DJ, Thomas NS, Mackay DJG, Jones HP, Waterham HR, 36. Jessen B, Maul-Pavicic A, Ufheil H, Vraetz T, Enders A, Lehmberg K, et al. et al. Zellweger syndrome resulting from maternal isodisomy of chromosome Subtle differences in CTL cytotoxicity determine susceptibility to 1. Am J Med Genet Part A (2007) 143A:2172–7. doi: 10.1002/ajmg.a.31912 hemophagocytic lymphohistiocytosis in mice and humans with Chediak- 28. GeneCards. Human Genes | Gene Database | Gene Search . Available at: Higashi syndrome. Blood (2011) 118:4620–9. doi: 10.1182/blood-2011-05- https://www.genecards.org/ (Accessed March 4, 2021). 356113 29. Niida Y, Ozaki M, Shimizu M, Ueno K, Tanaka T. Classification of 37. Robinson WP. Mechanisms leading to uniparental disomy and their clinical uniparental isodisomy patterns that cause autosomal recessive disorders: consequences. BioEssays (2000) 22:452–9. doi: 10.1002/(SICI)1521-1878 Proposed mechanisms of different proportions and parental origin in each (200005)22:5<452::AID-BIES7>3.0.CO;2-K pattern. Cytogenet Genome Res (2018) 154:137–46. doi: 10.1159/ 38. Nakka P, Pattillo Smith S, O'Donnell-Luria AH, McManus KF, Agee M, 000488572 Auton A, et al. Characterization of Prevalence and Health Consequences of 30. Keren B, Chantot-Bastaraud S, Brioude F, Mach C, Fonteneau E, Azzi S, et al. Uniparental Disomy in Four Million Individuals from the General Population. SNP arrays in Beckwith–Wiedemann syndrome: An improved diagnostic Am J Hum Genet (2019) 105:921–32. doi: 10.1016/j.ajhg.2019.09.016 strategy. Eur J Med Genet (2013) 56:546–50. doi: 10.1016/J.EJMG.2013.06.005 39. Yauy K, de Leeuw N, Yntema HG, Pfundt R, Gilissen C. Accurate detection of 31. Henry I, Puech A, Riesewijk A, Ahnine L, Mannens M, Beldjord C, et al. clinically relevant uniparental disomy from exome sequencing data. Genet Somatic Mosaicism for Partial Paternal Isodisomy in Wiedemann-Beckwith Med (2020) 22:803–8. doi: 10.1038/s41436-019-0704-x Syndrome: A Post-Fertilization Event. Eur J Hum Genet (1993) 1:19–29. 40. Scuffins J, Keller-Ramey J, Dyer L, Douglas G, Torene R, Gainullin V, et al. doi: 10.1159/000472384 Uniparental disomy in a population of 32,067 clinical exome trios. Genet Med 32. Su J, Wang J, Fan X, Fu C, Zhang S, Zhang Y, et al. Mosaic UPD(7q)mat in a (2021) 1–7. doi: 10.1038/s41436-020-01092-8 patient with silver Russell syndrome. Mol Cytogenet (2017) 10:36. doi: 10.1186/s13039-017-0337-1 Conflict of Interest: The authors declare that the research was conducted in the 33. Eggermann T, Soellner L, Buiting K, Kotzot D. Mosaicism and uniparental absence of any commercial or financial relationships that could be construed as a disomy in prenatal diagnosis. Trends Mol Med (2015) 21:77–87. doi: 10.1016/ potential conflict of interest. j.molmed.2014.11.010 34. Conlin LK, Thiel BD, Bonnemann CG, Medne L, Ernst LM, Zackai EH, et al. Copyright © 2021 Boluda-Navarro, Ibáñez, Liquori, Franco-Jarava, Martı ́nez-Gallo, Mechanisms of mosaicism, chimerism and uniparental disomy identified by Rodrı ́guez-Vega, Teresa, Carreras, Such, Zúñiga, Colobran and Cervera. This is an single nucleotide polymorphism array analysis. Hum Mol Genet (2010) open-access article distributed under the terms of the Creative Commons Attribution 19:1263–75. doi: 10.1093/hmg/ddq003 License (CC BY). The use, distribution or reproduction in other forums is permitted, 35. Aricò M, Janka G, Fischer A, Henter JI, Blanche S, Elinder G, et al. provided the original author(s) and the copyright owner(s) are credited and that the Hemophagocytic lymphohistiocytosis. Report of 122 children from the original publication in this journal is cited, in accordance with accepted academic International Registry. FHL Study Group of the Histiocyte Society. practice. No use, distribution or reproduction is permitted which does not comply with Leukemia (1996) 10:197–203. these terms. Frontiers in Immunology | www.frontiersin.org 9 March 2021 | Volume 12 | Article 625591