A homozygous variant in CHMP3 is associated with complex hereditary spastic paraplegia.

BACKGROUND: Monogenic neurodegenerative diseases represent a heterogeneous group of disorders caused by mutations in genes involved in various cellular functions including autophagy, which mediates degradation of cytoplasmic contents by their transport into lysosomes. Abnormal autophagy is associated with hereditary ataxia and spastic paraplegia, amyotrophic lateral sclerosis and frontal dementia, characterised by intracellular accumulation of non-degraded proteins. We investigated the genetic basis of complex HSP in a consanguineous family of Arab-Muslim origin, consistent with autosomal recessive inheritance. METHODS: Exome sequencing was followed by variant filtering and Sanger sequencing for validation and familial segregation. Studies for mRNA and protein expression used real-time PCR and immunoblots. Patients' primary fibroblasts were analysed using electron microscopy, immunofluorescence, western blot analysis and ectopic plasmid expression for its impact on autophagy. RESULTS: We identified a homozygous missense variant in CHMP3 (Chr2:86507484 GRCh38 (NM_016079.4): c.518C>T, p.Thr173Ile), which encodes CHMP3 protein. Segregation analysis validated the presence of the homozygous variant in five affected individuals, while healthy family members were found either heterozygous or wild type for this variant. Primary patient's fibroblasts showed significantly reduced levels of CHMP3. Electron microscopy disclosed accumulation of endosomes, autophagosomes and autolysosomes in patient's fibroblasts, which correlated with higher levels of autophagy markers, p62 and LC3-II. Ectopic expression of wild-type CHMP3 in primary patient fibroblasts led to reduction of the p62 particles accumulation and number of endosomes and autophagosomes compared with control. CONCLUSIONS: Reduced level of CHMP3 is associated with complex spastic paraplegia phenotype, through aberrant autophagy mechanisms.

The effect of a prior e-learning tool on genetic counseling outcomes in diverse ethnic couples with abnormal Down syndrome screening tests: A randomized controlled trial.

Genetic counseling (GC) following abnormal Down syndrome (DS) screening tests aims to ensure learning of complex medical concepts and discussion of counselees' personal desires. Pre-GC use of electronic learning tools (e-learning tools) can facilitate GC sessions by allowing more time for dialogue rather than learning medical and genetic concepts, enabling greater focus on the counselee's decisional, psychological, and personal needs. Few studies have investigated such tools for DS screening tests and those who have focused on screening uptake rather than abnormal results and implications. This study evaluated prenatal GC outcomes following implementation of an e-learning tool utilizing an educational animated movie for couples of varied ethnic backgrounds in northern Israel, with abnormal DS screening tests. E-learning tool impact was assessed as knowledge level, informed choices, satisfaction with the intervention and GC process, the state of anxiety and duration of the GC meeting. The 321 study participants were randomized to three groups: animation movie, booklet, and control. All participants had been asked to complete pre- and post-counseling questionnaires. Outcome scores were compared between the research groups. Results showed increased knowledge level in general among participants in the animation group; among minority participants, the highest knowledge level was in the animation group. Anxiety levels and informed choices were not statistically different among the groups. However, watching the animation, Jewish ethnicity, good level of genetic literacy, and academic degree were significant predictors of informed choice, and those who watched the animation were three times more likely to make an informed choice than the control group. Our findings suggest that this e-learning tool is efficient and acceptable for the general population. Special attention is needed for minorities with lower genetic literacy and education.

Potential di-genic contribution to guttate leukoderma as the predominant feature of epidermolysis bullosa simplex.

Inherited epidermolysis bullosa (EB) simplex is a heterogeneous group of skin fragility disorders caused by mutations in genes encoding cell-cell or cell-matrix adhesion proteins. A recently identified, rare subtype of EB simplex is due to bi-allelic mutations in the EXPH5 gene, which encodes exophilin5, an effector protein of the Rab27B GTPase involved in intracellular vesicle trafficking and exosome secretion. The EXPH5 EB subtype is characterized by early-onset skin blisters and scars, mainly on extremities, and varying degrees of pigmentary alterations. Here, we present a 31-year-old female with diffuse guttate hypopigmentation on the trunk and extremities since early childhood, with no apparent blisters or scars. We employed whole exome sequencing of germline DNA extracted from the patient's leukocytes to determine the genetic aetiology of the phenotype. A novel homozygous variant in EXPH5, c.1153C>T causing a premature stop codon at amino acid Glutamine 385, was identified. Histologic examination after skin pricking disclosed focal keratinocyte detachment typical to EB. Additionally, we identified a deleterious-predicted variant in ENPP1, a gene associated with disturbed transfer of melanosomes to keratinocytes in Cole disease. Our report expands the clinical spectrum of inherited EB simplex with a possible di-genic synergism contributing to co-presentation with guttate leukoderma.

Acral peeling in Nagashima type palmo-plantar keratosis patients reveals the role of serine protease inhibitor B 7 in keratinocyte adhesion.

Acral peeling skin syndrome (APSS) is a heterogenous group of genodermatoses, manifested by peeling of palmo-plantar skin and occasionally associated with erythema and epidermal thickening. A subset of APSS is caused by mutations in protease inhibitor encoding genes, resulting in unopposed protease activity and desmosomal degradation and/or mis-localization, leading to enhanced epidermal desquamation. We investigated two Arab-Muslim siblings with mild keratoderma and prominent APSS since infancy. Genetic analysis disclosed a homozygous mutation in SERPINB7, c.796C > T, which is the founder mutation in Nagashima type palmo-plantar keratosis (NPPK). Although not previously formally reported, APSS was found in other patients with NPPK. We hypothesized that loss of SERPINB7 function might contribute to the peeling phenotype through impairment of keratinocyte adhesion, similar to other protease inhibitor mutations that cause APSS. Mis-localization of desmosomal components was observed in a patient plantar biopsy compared with a biopsy from an age- and gender-matched healthy control. Silencing of SERPINB7 in normal human epidermal keratinocytes led to increased cell sheet fragmentation upon mechanical stress. Immunostaining showed reduced expression of desmoglein 1 and desmocollin 1. This study shows that in addition to stratum corneum perturbation, loss of SERPINB7 disrupts desmosomal components, which could lead to desquamation, manifested by skin peeling.

Concomitant variants in NF1, LZTR1 and GNAZ genes probably contribute to the aggressiveness of plexiform neurofibroma and warrant treatment with MEK inhibitor.

Neurofibromatosis 1 (NF1) is caused by germline mutations in the NF1 gene and manifests as proliferation of various tissues, including plexiform neurofibromas. The plexiform neurofibroma phenotype varies from indolent to locally aggressive, suggesting contributions of other modifiers in addition to somatic loss of NF1. In this study, we investigated a life-threatening plexiform neurofibroma in a 9-month-old female infant with NF1. Germline mutations in two RASopathy-associated genes were identified using whole-exome sequencing-a de novo pathogenic variant in the NF1 gene, and a known pathogenic variant in the LZTR1 gene. Somatic analysis of the plexiform neurofibroma revealed NF1 loss of heterozygosity and a variant in GNAZ, a gene encoding a G protein-coupled receptor. Cells expressing mutant GNAZ exhibited increased ERK 1/2 activation compared to those expressing wild-type GNAZ. Taken together, we suggest the variants in NF1, LZRT1 and GNAZ act synergistically in our patient, leading to MAPK pathway activation and contributing to the severity of the patient's plexiform neurofibromatosis. After treatment with the MEK inhibitor, trametinib, a prominent clinical improvement was observed in this patient. This case study contributes to the knowledge of germline and somatic non-NF1 variants affecting the NF1 clinical phenotype and supports use of personalized, targeted therapy.

The landscape of autosomal recessive variants in an isolated community: Implications for population screening for reproductive purposes.

As a result of the preference for consanguineous/endogamous marriages, the Israeli Arab population is composed of isolated communities with relatively frequent autosomal recessive (AR) conditions in each community. Clinical diagnosis of affected individuals has uncovered the pathogenic variants throughout the years. We investigated the diversity of pathogenic AR variants in a single village in northern Israel by exome analysis of 50 random, healthy adults descendants of the founders. Only likely pathogenic and pathogenic variants in known AR genes were selected. In this study 48 AR variants were found, of which 12 had been previously diagnosed in patients from this village, and for 11 with a frequency compatible with the frequency already known. Among the other 36 variants, 12 had been previously diagnosed in affected individuals in other Arab communities in Israel and 24 variants had not been previously characterized in this population. Of the 35 variants associated with conditions of moderate-severe medical consequences, only eight were known previously in this village. These findings emphasize the importance to better delineate the conditions at risk in a defined community, in particular for the development of preventive measures such as screening tests for reproductive couples, and for genetic counseling.

An Update on the Cutaneous Manifestations of Darier Disease.

BACKGROUND: Knowledge about the clinical features of Darier disease, an orphan autosomal-dominant genetic disorder, is sparse and has been evaluated only in few studies. OBJECTIVES: To investigate the clinical features of a large group of patients with Darier disease, and to explore for associations between disease characteristics and severity of the disease. METHODS: Seventy-six individuals with Darier disease were evaluated utilizing a structured questionnaire-based interview, a physical examination, and a retrospective assessment of their medical records. RESULTS: The most frequent locations of lesions were hands (99%) and fingernails (93%). Wart-like lesions on the hands were more visible after soaking them in water for 5 minutes, we therefore named this phenomenon the "wet hand sign". Oral involvement was found in 43% of patients, while 48% of women and 16% of men showed genital lesions. Patients with severe Darier disease had a tenfold greater risk of developing genital lesions than those with mild disease (P = .01). Most patients (88%) in our study exhibited a combination of the four types of the disease patterns of distribution (flexural, seborrheic, nevoid, and acral). CONCLUSIONS: Documentation of disease on the hands and fingernails provides a highly sensitive means to aid in the diagnosis of Darier disease. It is important to evaluate mucosal lesions including genital and oral mucosa.

Chromosomal microarray should be performed for cases of fetal short long bones detected prenatally.

PURPOSE: To investigate the prevalence of pathogenic and likely-pathogenic variants detected by chromosomal microarray analysis (CMA), among pregnancies with fetal short long bones diagnosed by ultrasound. METHODS: The study cohort was based on cases of chromosomal microarray analyses performed nationwide for the indication of short long bones. RESULTS: CMA was performed in 66 cases of short long bones. There were 4 cases with a pathogenic/likely pathogenic result (6%). The rate of chromosomal abnormalities was significantly higher compared to the background risk for copy number variations (CNVs) in pregnancies with no sonographic anomalies (P < 0.001). The yield of CMA in our cohort was significantly higher for both isolated and non-isolated cases, for cases in which the lowest estimated bone length percentile was above the 3rd percentile (below 5th percentile), and for cases diagnosed with short long bones after 22 weeks but not for cases diagnosed after 24 weeks. CONCLUSION: The yield of CMA in cases with short long bones (both isolated and non-isolated) is significantly higher than the background risk for chromosomal anomalies in pregnancies with no sonographic anomalies. This suggests that CMA should be offered in pregnancies with a diagnosis of fetal short long bones.

Spectrum of genes for inherited hearing loss in the Israeli Jewish population, including the novel human deafness gene ATOH1.

Mutations in more than 150 genes are responsible for inherited hearing loss, with thousands of different, severe causal alleles that vary among populations. The Israeli Jewish population includes communities of diverse geographic origins, revealing a wide range of deafness-associated variants and enabling clinical characterization of the associated phenotypes. Our goal was to identify the genetic causes of inherited hearing loss in this population, and to determine relationships among genotype, phenotype, and ethnicity. Genomic DNA samples from informative relatives of 88 multiplex families, all of self-identified Jewish ancestry, with either non-syndromic or syndromic hearing loss, were sequenced for known and candidate deafness genes using the HEar-Seq gene panel. The genetic causes of hearing loss were identified for 60% of the families. One gene was encountered for the first time in human hearing loss: ATOH1 (Atonal), a basic helix-loop-helix transcription factor responsible for autosomal dominant progressive hearing loss in a five-generation family. Our results show that genomic sequencing with a gene panel dedicated to hearing loss is effective for genetic diagnoses in a diverse population. Comprehensive sequencing enables well-informed genetic counseling and clinical management by medical geneticists, otolaryngologists, audiologists, and speech therapists and can be integrated into newborn screening for deafness.

The yield of chromosomal microarray testing for cases of abnormal fetal head circumference.

Objectives: Chromosomal microarray analysis (CMA) is the method of choice for genetic work-up in cases of fetal malformations. We assessed the detection rate of CMA in cases of abnormal fetal head circumference (HC). Methods: The study cohort was based on 81 cases of amniocenteses performed throughout Israel for the indication of microcephaly (53) or macrocephaly (28), from January 2015 through December 2018. We retrieved data regarding the clinical background, parental HCs and work-up during the pregnancy from genetic counseling summaries and from patients' medical records. Results: There was only one likely pathogenic CMA result (1.89%): a 400-kb microdeletion at 16p13.3 detected in a case of isolated microcephaly. No pathogenic results were found in the macrocephaly group. Most fetuses with microcephaly were female (87.8%), while the majority with macrocephaly were males (86.4%). Conclusions: The results imply that CMA analysis in pregnancies with microcephaly may carry a small yield compared to other indications. Regarding macrocephaly, our cohort was too small to draw conclusions. In light of the significant gender effect on the diagnosis of abnormal HC, standardization of fetal HC charts according to fetal gender may normalize cases that were categorized outside the normal range and may increase the yield of CMA for cases of abnormal HC.

Clinical, radiological, and genetic characteristics of 16 patients with ACO2 gene defects: Delineation of an emerging neurometabolic syndrome.

Mitochondrial aconitase is the second enzyme in the tricarboxylic acid (TCA) cycle catalyzing the interconversion of citrate into isocitrate and encoded by the nuclear gene ACO2. A homozygous pathogenic variant in the ACO2 gene was initially described in 2012 resulting in a novel disorder termed "infantile cerebellar retinal degeneration" (ICRD, OMIM#614559). Subsequently, additional studies reported patients with pathogenic ACO2 variants, further expanding the genetic and clinical spectrum of this disorder to include milder and later onset manifestations. Here, we report an international multicenter cohort of 16 patients (of whom 7 are newly diagnosed) with biallelic pathogenic variants in ACO2 gene. Most patients present in early infancy with severe truncal hypotonia, truncal ataxia, variable seizures, evolving microcephaly, and ophthalmological abnormalities of which the most dominant are esotropia and optic atrophy with later development of retinal dystrophy. Most patients remain nonambulatory and do no acquire any language, but a subgroup of patients share a more favorable course. Brain magnetic resonance imaging (MRI) is typically normal within the first months but global atrophy gradually develops affecting predominantly the cerebellum. Ten of our patients were homozygous to the previously reported c.336C>G founder mutation while the other six patients were all compound heterozygotes displaying 10 novel mutations of whom 2 were nonsense predicting a deleterious effect on enzyme function. Structural protein modeling predicted significant impairment in aconitase substrate binding in the additional missense mutations. This study provides the most extensive cohort of patients and further delineates the clinical, radiological, biochemical, and molecular features of ACO2 deficiency.

A homozygous TTN gene variant associated with lethal congenital contracture syndrome.

Pathogenic variants in the TTN gene have been reported to cause various cardiomyopathies and a range of skeletal muscle diseases, collectively known as titinopathies. We evaluated a consanguineous family multiple members affected with a lethal congenital contracture syndrome. Using exome sequencing, we identified a homozygous c.36122delC (p. P12041Lfs*20) variant in exon 167 in the fetal IC isoform of TTN. The finding expands the phenotypes that can be caused by pathogenic variants TTN, which should be considered in lethal congenital contracture syndromes, arthrogryposis multiplex congenita, congenital myopathies, and hydrops fetalis.

TBCK-related intellectual disability syndrome: Case study of two patients.

There is a significant level of genetic heterogeneity underlying the phenotype of nonspecific hypotonia with severe intellectual disability. Exome sequencing has proven to be a powerful tool for identifying the underlying molecular basis of such nonspecific, abnormal neurological phenotypes. Mutations in the TBCK gene have been reported associated with very poor, if any, psychomotor development, poor speech, and inability to walk independently. We describe the long-term phenotypic evolution of a severe nonspecific neurodevelopmental disorder in two siblings born to an Arab-Moslem family living in northern Israel. Exome sequencing led to identification of a novel homozygous mutation: c.1854delT in the TBCK gene. Abnormal elevated ß-HCG was found in the maternal serum during the two pregnancies, a finding that has not been reported before. These individuals present with severe intellectual disability, no speech, hypotonia, convulsions, and lack of any independent daily skills. © 2016 Wiley Periodicals, Inc.

Fatal infantile mitochondrial encephalomyopathy, hypertrophic cardiomyopathy and optic atrophy associated with a homozygous OPA1 mutation.

BACKGROUND: Infantile-onset encephalopathy and hypertrophic cardiomyopathy caused by mitochondrial oxidative phosphorylation defects are genetically heterogeneous with defects involving both the mitochondrial and nuclear genomes. OBJECTIVE: To identify the causative genetic defect in two sisters presenting with lethal infantile encephalopathy, hypertrophic cardiomyopathy and optic atrophy. METHODS: We describe a comprehensive clinical, biochemical and molecular genetic investigation of two affected siblings from a consanguineous family. Molecular genetic analysis was done by a combined approach involving genome-wide autozygosity mapping and next-generation exome sequencing. Biochemical analysis was done by enzymatic analysis and Western blot. Evidence for mitochondrial DNA (mtDNA) instability was investigated using long-range and real-time PCR assays. Mitochondrial cristae morphology was assessed with transmission electron microscopy. RESULTS: Both affected sisters presented with a similar cluster of neurodevelopmental deficits marked by failure to thrive, generalised neuromuscular weakness and optic atrophy. The disease progression was ultimately fatal with severe encephalopathy and hypertrophic cardiomyopathy. Mitochondrial respiratory chain complex activities were globally decreased in skeletal muscle biopsies. They were found to be homozygous for a novel c.1601T>G (p.Leu534Arg) mutation in the OPA1 gene, which resulted in a marked loss of steady-state levels of the native OPA1 protein. We observed severe mtDNA depletion in DNA extracted from the patients' muscle biopsies. Mitochondrial morphology was consistent with abnormal mitochondrial membrane fusion. CONCLUSIONS: We have established, for the first time, a causal link between a pathogenic homozygous OPA1 mutation and human disease. The fatal multisystemic manifestations observed further extend the complex phenotype associated with pathogenic OPA1 mutations, in particular the previously unreported association with hypertrophic cardiomyopathy. Our findings further emphasise the vital role played by OPA1 in mitochondrial biogenesis and mtDNA maintenance.

[OXALATE STONES ARE PREVALENT AMONG DRUZE AND MUSLIM ARABS IN THE GALILEE].

INTRODUCTION: Primary Hyperoxaluria type I (PH1) is a rare autosomal recessive disease caused by lack or dysfunction of the liver peroxisomal enzyme alanine: glyoxylate aminotransferase, AGT. AIMS: To conduct clinical and genetic characterization of Druze and Muslim Arab patients with PH1 in Northern Israel. METHODS: In the last 20 years, 36 children and families were diagnosed and treated in the Nephrology-Genetic Clinic at the Galilee Medical Center. Clinical evaluation for nephrocalcinosis with/without renal stones, elevated excretion of oxalate and glycolate in urine, and genetic workup were performed. Treatment included hemodialysis, and/or peritoneal dialysis. Some patients were directed to preemptive liver transplantation or to combined liver and kidney transplantation. Genetic counseling and prenatal diagnosis were conducted. RESULTS: Thirty-six patients, from newborns to adults in their 20's, were diagnosed with PH1. They represent 38.8% of patients in the pediatric-dialysis unit. The genetic variant in the AGXT gene causing their disease was identified. Nine prenatal diagnoses were performed, and a genetic screening program was implemented in four Druze villages in the Galilee and Golan Heights. CONCLUSIONS: PH1 is a prevalent disease among Druze and Muslim Arabs in northern Israel. Genetic diagnosis is the gold standard and enables early diagnosis and treatment. Genotype-phenotype correlations are complex. Population screening programs provide an important tool for prevention. DISCUSSION: The "genetic islands" of PH1 in northern Israel require a community-based medical approach for the prevention of the disease and the treatment of presymptomatic patients for better prognosis.

A PIGN mutation responsible for multiple congenital anomalies-hypotonia-seizures syndrome 1 (MCAHS1) in an Israeli-Arab family.

Mutations in the PIGN gene involved in the glycosylphoshatidylinositol (GPI) anchor biosynthesis pathway cause Multiple Congenital Anomalies-Hypotonia-Seizures syndrome 1 (MCAHS1). The syndrome manifests developmental delay, hypotonia, and epilepsy, combined with multiple congenital anomalies. We report on the identification of a homozygous novel c.755A>T (p.D252V) deleterious mutation in a patient with Israeli-Arab origin with MCAHS1. The mutated PIGN caused a significant decrease of the overall GPI-anchored proteins and CD24 expression. Our results, strongly support previously published data, that partial depletion of GPI-anchored proteins is sufficient to cause severe phenotypic expression.

Further insight into the phenotype associated with a mutation in the ORC6 gene, causing Meier-Gorlin syndrome 3.

Mutations in genes encoding the origin recognition complex subunits cause Meier-Gorlin syndrome. The disease manifests a triad of short stature, small ears, and small and/or absent patellae with variable expressivity. We report on the identification of a homozygous deleterious mutation in the ORC6 gene in previously described fetuses at the severe end of the Meier-Gorlin spectrum. The phenotype included severe intrauterine growth retardation, dislocation of knees, gracile bones, clubfeet, and small mandible and chest. To date, the clinical presentation of ORC6-associated Meier-Gorlin syndrome has been mild compared to other the phenotype associated with other loci. The present report expands the clinical phenotype associated with ORC6 mutations to include severely abnormal embryological development suggesting a possible genotype-phenotype correlation.

Novel mutation in TSPAN12 leads to autosomal recessive inheritance of congenital vitreoretinal disease with intra-familial phenotypic variability.

Developmental malformations of the vitreoretinal vasculature are a heterogeneous group of conditions with various modes of inheritance, and include familial exudative vitreoretinopathy (FEVR), persistent fetal vasculature (PFV), and Norrie disease. We investigated a large consanguineous kindred with multiple affected individuals exhibiting variable phenotypes of abnormal vitreoretinal vasculature, consistent with the three above-mentioned conditions and compatible with autosomal recessive inheritance. Exome sequencing identified a novel c.542G > T (p.C181F) apparently mutation in the TSPAN12 gene that segregated with the ocular disease in the family. The TSPAN12 gene was previously reported to cause dominant and recessive FEVR, but has not yet been associated with other vitreoretinal manifestations. The intra-familial clinical variability caused by a single mutation in the TSPAN12 gene underscores the complicated phenotype-genotype correlation of mutations in this gene, and suggests that there are additional genetic and environmental factors involved in the complex process of ocular vascularization during embryonic development. Our study supports considering PFV, FEVR, and Norrie disease a spectrum of disorders, with clinical and genetic overlap, caused by mutations in distinct genes acting in the Norrin/ß-catenin signaling pathway.

Lack of mitochondrial complex I assembly factor NDUFAF2 results in a distinctive infantile-onset brainstem neurodegenerative disease with early lethality.

BACKGROUND: Congenital disorders of the mitochondrial respiratory chain are a heterogeneous group of inborn errors of metabolism. Among them, NADH:ubiquinone oxidoreductase (complex I, CI) deficiency is the most common. Biallelic pathogenic variants in NDUFAF2, encoding the nuclear assembly CI factor NDUFAF2, were initially reported to cause progressive encephalopathy beginning in infancy. Since the initial report in 2005, less than a dozen patients with NDUFAF2-related disease have been reported. METHODS: Clinical, biochemical, and neuroradiological features of four new patients residing in Northern Israel were collected during 2016-2022 at Emek Medical Center. Enzymatic activities of the five respiratory-chain complexes were determined in isolated fibroblast mitochondria by spectrophotometric methods. Western blot analyses were conducted with anti-human NDUFAF2 antibody; antibody against the mitochondrial marker VDAC1 was used as a loading control. Genetic studies were performed by chromosome microarray analysis using Affymetrix CytoScan 750 K arrays. RESULTS: All four patients presented with infantile-onset growth retardation, ophthalmological impairments with nystagmus, strabismus (starting between 5 and 9 months), and further progressed to life-threatening episodes of apnea usually triggered by trivial febrile illnesses (between 10 and 18 months) with gradual loss of acquired developmental milestones (3 of 4 patients). Serial magnetic-resonance imaging studies in two of the four patients showed a progressive pattern of abnormal T2-weighted hyperintense signals involving primarily the brainstem, the upper cervical cord, and later, the basal ganglia and thalami. Magnetic-resonance spectroscopy in one patient showed an increased lactate peak. Disease progression was marked by ventilatory dependency and early lethality. 3 of the 4 patients tested, harbored a homozygous 142-kb partial interstitial deletion that omits exons 2-4 of NDUFAF2. Mitochondrial CI activity was significantly decreased in the only patient tested. Western blot analysis disclosed the absence of NDUFAF2 protein compared to normal controls. In addition, we reviewed all 10 previously reported NDUFAF2-deficient cases to better characterize the disease. CONCLUSIONS: Biallelic loss-of-function mutations in NDUFAF2 result in a distinctive phenotype in the spectrum of Leigh syndrome with clinical and neuroradiological features that are primarily attributed to progressive brainstem damage.

Persistent Cutaneous Lesions of Darier Disease and Second-Hit Somatic Variants in ATP2A2 Gene.

Importance: Darier disease (DD) is a rare genetic skin disorder caused by heterozygous variants in the ATP2A2 gene. Clinical manifestations include recurrent hyperkeratotic papules and plaques that occur mainly in seborrheic areas. Although some of the lesions wax and wane in response to environmental factors, others are severe and respond poorly to therapy. Objective: To investigate the molecular mechanism underlying the persistency of skin lesions in DD. Design, Setting, and Participants: In this case series, DNA was extracted from unaffected skin, transient and persistent lesional skin, and blood from 9 patients with DD. Genetic analysis was used using paired-whole exome sequencing of affected skin and blood or by deep sequencing of ATP2A2 of affected skin. Chromosomal microarray analysis was used to reveal copy number variants and loss of heterozygosity. All variants were validated by Sanger sequencing or restriction fragment length polymorphism. Interventions or Exposures: Paired whole-exome sequencing and deep sequencing of ATP2A2 gene from blood and skin samples isolated from persistent, transient lesions and unaffected skin in patients with DD. Main Outcomes and Measures: Germline and somatic genomic characteristics of persistent and transient cutaneous lesions in DD. Results: Of 9 patients with DD, all had heterozygous pathogenic germline variants in the ATP2A2 gene, 6 were female. Participant age ranged from 40 to 69 years on enrollment. All 11 persistent skin lesions were associated with second-hit somatic variants in the ATP2A2 gene. The somatic variants were classified as highly deleterious via combined annotation-dependent depletion (CADD) scores or affect splicing, and 3 of them had been previously described in patients with DD and acrokeratosis verruciformis of Hopf. Second-hit variants in the ATP2A2 gene were not identified in the transient lesions (n = 2) or the normal skin (n = 2). Conclusions and Relevance: In this study, persistent DD lesions were associated with the presence of second-hit somatic variants in the ATP2A2 gene. Identification of these second-hit variants offers valuable insight into the underlying mechanisms that contribute to the lasting nature of persistent DD lesions.