Case report: Novel insights into hemorrhagic destruction of the brain, subependymal calcification, and cataracts disease.

Introduction: Pathogenic variants of the junctional adhesion molecule 3 (JAM3/JAM-C; OMIM#606871) is the cause of the rare recessive disorder called hemorrhagic destruction of the brain, subependymal calcification, and cataracts (HDBSCC, OMIM#613730) disease. A similar phenotype is universal, including congenital cataracts and brain hemorrhages with high mortality rate in the first few weeks of life and with a poor neurologic outcome in survivors. We aim to describe and enlighten novel phenotype and genotype of a new patient and review the literature regarding all reported patients worldwide. Case report: We report the case of a prenatal and postnatal phenotype of a new patient with a novel pathogenic loss-of-function variant in JAM3, who presented prenatally with cataracts and brain anomalies and postnatally with brain hemorrhages, failure to thrive (FTT), progressive microcephaly, recurrent posterior capsule opacities, and auditory neuropathy. Discussion: This study enlightens novel possible functions of JAM3 in the normal development of the brain, the ocular lenses, the auditory system, and possibly the gastrointestinal tract. This study is the first to report of cataracts evident in as early as 23 weeks of gestation and a rare phenomenon of recurrent posterior capsule opacities despite performing recurrent posterior capsulectomy and anterior vitrectomy. We suggest that auditory neuropathy, which is reported here for the first time, is part of the phenotype of HDBSCC, probably due to an endothelial microvasculature disruption of the peripheral eighth nerve or possibly due to impaired nerve conduction from the synapse to the brainstem. Conclusions: Prenatal cataracts, brain anomalies, FTT, and auditory neuropathy are part of the phenotype of the HDBSCC disease. We suggest including JAM3 in the gene list known to cause congenital cataracts, brain hemorrhages, and hearing loss. Further studies should address the auditory neuropathy and FTT phenomena in knockout mice models. We further suggest performing comprehensive ophthalmic, audiologic, and gastroenterologic evaluations for living patients worldwide to further confirm these novel phenomena in this rare entity.

Long-term outcomes after pre-emptive liver transplantation in primary hyperoxaluria type 1.

BACKGROUND: Primary hyperoxaluria type 1 (PH1) is an autosomal recessive disease caused by the liver defect of oxalate metabolism, which leads to kidney failure and systemic manifestations. Until recently, liver transplantation was the only definitive treatment. The timing of liver transplantation can be early, while kidney function is still normal (pre-emptive liver transplantation-PLT), or when the patient reaches stage 5 chronic kidney disease (CKD) and needs combined liver-kidney transplantation. We aimed to determine the long-term kidney outcomes of PLT in PH1 patients. METHODS: A retrospective single-center study of PH1 patients who were followed in our center between 1997 and 2017. We compared the kidney outcomes of patients who underwent PLT to those who presented with preserved kidney function and did not undergo PLT. RESULTS: Out of 36 PH1 patients, 18 patients were eligible for PLT (eGFR > 40 mL/min/1.73 m2 at the time of diagnosis). Seven patients underwent PLT (PLT group), while 11 continued conservative treatments (PLTn group). In the PLT group, the median eGFR at the time of PLT and at the end of the follow-up period (14-20 years) was 72 (range 50-89) and 104 (range 86-108) mL/min/1.73 m2, respectively, and no patient died or reached stage 5 CKD. In the PLTn group, eight patients (72.7%) reached stage 5 CKD (median time to kidney replacement therapy was 11 years), and two patients died from disease complications (18.2%). CONCLUSIONS: Pre-emptive liver transplantation preserved kidney function in patients with PH1 in our cohort. Early intervention can prevent kidney failure and systemic oxalosis in PH1. A higher resolution version of the Graphical abstract is available as Supplementary information.

Long term ophthalmic complications of distal arthrogryposis type 5D.

BACKGROUND: Distal Arthrogryposis type 5D (DA5D) is a rare genetic disease, expressed phenotypically by skeletal and ocular abnormalities. MATERIALS AND METHODS: Two sisters, ages 42 and 46 years old, were ascertained, both diagnosed with arthrogryposis and unusual ophthalmic late expressions of the disease. They were examined and followed up by both ophthalmologists and medical geneticists. Molecular analysis was performed and population screening followed among healthy individuals of the same ethnic background who reside in the same village. RESULTS: The two sisters expressed myogenic ptosis with poor levator palpebrae function, limitation in up gaze, lagophthalmos, refractive errors, corneal scarring and vascularization along with severe distal arthrogryposis. The newly reported features were: significant lower lid retraction, causing inferior scleral show. Sanger sequencing of the coding regions of ECEL1 gene revealed a homozygous deletion of 46 bps. The carrier frequency is 1:24 (4.2% carriers) in the probands' village. CONCLUSIONS: We diagnosed two patients with DA5D carrying a homozygous pathogenic genetic variant previously reported only once. We report the late ophthalmologic manifestations of this rare disorder and emphasize the importance to recognize possible long-term ophthalmic complications. Measures are needed to diagnose this rare disorder at a younger age and to address ophthalmic and orthopedic complications that might be prevented. We revealed the causative genetic variant and a carrier frequency of 1:24 for DA5D, in the probands' village, thus enabling accurate genetic counselling and justifying genetic testing to the residents of this village as a diagnostic and preventive measure.

Familial Early-Onset Alzheimer's Caused by Novel Genetic Variant and APP Duplication: A Cross-Sectional Study.

BACKGROUND: The clinical characteristics of symptomatic and asymptomatic carriers of early- onset autosomal dominant Alzheimer's (EOADAD) due to a yet-undescribed chromosomal rearrangement may add to the available body of knowledge about Alzheimer's disease and may enlighten novel and modifier genes. We report the clinical and genetic characteristics of asymptomatic and symptomatic individuals carrying a novel APP duplication rearrangement. METHODS: Individuals belonging to a seven-generation pedigree with familial cognitive decline or intracerebral hemorrhages were recruited. Participants underwent medical, neurological, and neuropsychological evaluations. The genetic analysis included chromosomal microarray, Karyotype, fluorescence in situ hybridization, and whole genome sequencing. RESULTS: Of 68 individuals, six females presented with dementia, and four males presented with intracerebral hemorrhage. Of these, nine were found to carry Chromosome 21 copy number gain (chr21:27,224,097-27,871,284, GRCh37/hg19) including the APP locus (APP-dup). In seven, Chromosome 5 copy number gain (Chr5: 24,786,234-29,446,070, GRCh37/hg19) (Chr5-CNG) cosegregated with the APP-dup. Both duplications co-localized to chromosome 18q21.1 and segregated in 25 pre-symptomatic carriers. Compared to non-carriers, asymptomatic carriers manifested cognitive decline in their mid-thirties. A third of the affected individuals carried a diagnosis of a dis-immune condition. CONCLUSION: APP extra dosage, even in isolation and when located outside chromosome 21, is pathogenic. The clinical presentation of APP duplication varies and may be gender specific, i.e., ICH in males and cognitive-behavioral deterioration in females. The association with immune disorders is presently unclear but may prove relevant. The implication of Chr5-CNG co-segregation and the surrounding chromosome 18 genetic sequence needs further clarification.

NGLY1 Deficiency Zebrafish Model Manifests Abnormalities of the Nervous and Musculoskeletal Systems.

Background: NGLY1 is an enigmatic enzyme with multiple functions across a wide range of species. In humans, pathogenic genetic variants in NGLY1 are linked to a variable phenotype of global neurological dysfunction, abnormal tear production, and liver disease presenting the rare autosomal recessive disorder N-glycanase deficiency. We have ascertained four NGLY1 deficiency patients who were found to carry a homozygous nonsense variant (c.1294G > T, p.Glu432*) in NGLY1. Methods: We created an ngly1 deficiency zebrafish model and studied the nervous and musculoskeletal (MSK) systems to further characterize the phenotypes and pathophysiology of the disease. Results: Nervous system morphology analysis has shown significant loss of axon fibers in the peripheral nervous system. In addition, we found muscle structure abnormality of the mutant fish. Locomotion behavior analysis has shown hypersensitivity of the larval ngly1 (-/-) fish during stress conditions. Conclusion: This first reported NGLY1 deficiency zebrafish model might add to our understanding of NGLY1 role in the development of the nervous and MSK systems. Moreover, it might elucidate the natural history of the disease and be used as a platform for the development of novel therapies.

A Founder Mutation in EHD1 Presents with Tubular Proteinuria and Deafness.

BACKGROUND: The endocytic reabsorption of proteins in the proximal tubule requires a complex machinery and defects can lead to tubular proteinuria. The precise mechanisms of endocytosis and processing of receptors and cargo are incompletely understood. EHD1 belongs to a family of proteins presumably involved in the scission of intracellular vesicles and in ciliogenesis. However, the relevance of EHD1 in human tissues, in particular in the kidney, was unknown. METHODS: Genetic techniques were used in patients with tubular proteinuria and deafness to identify the disease-causing gene. Diagnostic and functional studies were performed in patients and disease models to investigate the pathophysiology. RESULTS: We identified six individuals (5-33 years) with proteinuria and a high-frequency hearing deficit associated with the homozygous missense variant c.1192C>T (p.R398W) in EHD1. Proteinuria (0.7-2.1 g/d) consisted predominantly of low molecular weight proteins, reflecting impaired renal proximal tubular endocytosis of filtered proteins. Ehd1 knockout and Ehd1R398W/R398W knockin mice also showed a high-frequency hearing deficit and impaired receptor-mediated endocytosis in proximal tubules, and a zebrafish model showed impaired ability to reabsorb low molecular weight dextran. Interestingly, ciliogenesis appeared unaffected in patients and mouse models. In silico structural analysis predicted a destabilizing effect of the R398W variant and possible inference with nucleotide binding leading to impaired EHD1 oligomerization and membrane remodeling ability. CONCLUSIONS: A homozygous missense variant of EHD1 causes a previously unrecognized autosomal recessive disorder characterized by sensorineural deafness and tubular proteinuria. Recessive EHD1 variants should be considered in individuals with hearing impairment, especially if tubular proteinuria is noted.

Congenital Hypotonia: Cracking a SAGA of consanguineous kindred harboring four genetic variants.

BACKGROUND: We aimed to determine the molecular and biochemical basis of an extended highly consanguineous family with multiple children presenting severe congenital hypotonia. METHODS: Clinical investigations, homozygosity mapping, linkage analyses and whole exome sequencing, were performed. mRNA and protein levels were determined. Population screening was followed. RESULTS: We have identified a novel nonsense variant in NGLY1 in two affected siblings, and compound heterozygosity for three novel RYR1 variants in two affected sisters from another nuclear family within the broad pedigree. Population screening revealed a high prevalence of carriers for both diseases. The genetic variants were proven to be pathogenic, as demonstrated by western blot analyses. CONCLUSIONS: Revealing the genetic diagnosis enabled us to provide credible genetic counselling and pre-natal diagnosis to the extended family and genetic screening for this high-risk population. Whole exome/genome sequencing should be the first tier tool for accurate determination of the genetic basis of congenital hypotonia. Two different genetic disorders within a large consanguineous pedigree should be always considered.

Classical Xanthinuria in Nine Israeli Families and Two Isolated Cases from Germany: Molecular, Biochemical and Population Genetics Aspects.

Classical xanthinuria is a rare autosomal recessive metabolic disorder caused by variants in the XDH (type I) or MOCOS (type II) genes. Thirteen Israeli kindred (five Jewish and eight Arab) and two isolated cases from Germany were studied between the years 1997 and 2013. Four and a branch of a fifth of these families were previously described. Here, we reported the demographic, clinical, molecular and biochemical characterizations of the remaining cases. Seven out of 20 affected individuals (35%) presented with xanthinuria-related symptoms of varied severity. Among the 10 distinct variants identified, six were novel: c.449G>T (p.(Cys150Phe)), c.1434G>A (p.(Trp478*)), c.1871C>G (p.(Ser624*)) and c.913del (p.(Leu305fs*1)) in the XDH gene and c.1046C>T (p.(Thr349Ileu)) and c.1771C>T (p.(Pro591Ser)) in the MOCOS gene. Heterologous protein expression studies revealed that the p.Cys150Phe variant within the Fe/S-I cluster-binding site impairs XDH biogenesis, the p.Thr349Ileu variant in the NifS-like domain of MOCOS affects protein stability and cysteine desulfurase activity, while the p.Pro591Ser and a previously described p.Arg776Cys variant in the C-terminal domain affect Molybdenum cofactor binding. Based on the results of haplotype analyses and historical genealogy findings, the potential dispersion of the identified variants is discussed. As far as we are aware, this is the largest cohort of xanthinuria cases described so far, substantially expanding the repertoire of pathogenic variants, characterizing structurally and functionally essential amino acid residues in the XDH and MOCOS proteins and addressing the population genetic aspects of classical xanthinuria.

Challenges to effective and autonomous genetic testing and counseling for ethno-cultural minorities: a qualitative study.

BACKGROUND: The Arab population in Israel is a minority ethnic group with its own distinct cultural subgroups. Minority populations are known to underutilize genetic tests and counseling services, thereby undermining the effectiveness of these services among such populations. However, the general and culture-specific reasons for this underutilization are not well defined. Moreover, Arab populations and their key cultural-religious subsets (Muslims, Christians, and Druze) do not reside exclusively in Israel, but are rather found as a minority group in many European and North American countries. Therefore, focusing on the Arab population in Israel allows for the examination of attitudes regarding genetic testing and counseling among this globally important ethnic minority population. METHODS: We used a qualitative research method, employing individual interviews with 18 women of childbearing age from three religious subgroups (i.e., Druze, Muslim, and Christian) who reside in the Acre district, along with focus group discussions with healthcare providers (HCPs; 9 nurses and 7 genetic counselors) working in the same geographical district. RESULTS: A general lack of knowledge regarding the goals and practice of genetic counseling resulting in negative preconceptions of genetic testing was identified amongst all counselees. Counselors' objective of respecting patient autonomy in decision-making, together with counselees' misunderstanding of genetic risk data, caused uncertainty, frustration, and distrust. In addition, certain interesting variations were found between the different religious subgroups regarding their attitudes to genetic counseling. CONCLUSIONS: The study highlights the miscommunications between HCPs, particularly counselors from the majority ethno-cultural group, and counselees from a minority ethno-cultural group. The need for nuanced understanding of the complex perspectives of minority ethno-cultural groups is also emphasized. Such an understanding may enhance the effectiveness of genetic testing and counseling among the Arab minority group while also genuinely empowering the personal autonomy of counselees from this minority group in Israel and other countries.

De novo STXBP1 mutation in a child with developmental delay and spasticity reveals a major structural alteration in the interface with syntaxin 1A.

STXBP1, also known as Munc-18, is a master regulator of neurotransmitter release and synaptic function in the human brain through its direct interaction with syntaxin 1A. STXBP1 binds syntaxin 1A is an inactive conformational state. STXBP1 decreases its binding affinity to syntaxin upon phosphorylation, enabling syntaxin 1A to engage in the SNARE complex, leading to neurotransmitter release. STXBP1-related disorders are well characterized by encephalopathy with epilepsy, and a diverse range of neurological and neurodevelopmental conditions. Through exome sequencing of a child with developmental delay, hypotonia, and spasticity, we found a novel de novo insertion mutation of three nucleotides in the STXBP1 coding region, resulting in an additional arginine after position 39 (R39dup). Inconclusive results from state-of-the-art variant prediction tools mandated a structure-based approach using molecular dynamics (MD) simulations of the STXBP1-syntaxin 1A complex. Comparison of the interaction interfaces of the wild-type and the R39dup complexes revealed a reduced interaction surface area in the mutant, leading to destabilization of the protein complex. Moreover, the decrease in affinity toward syntaxin 1A is similar for the phosphorylated STXBP1 and the R39dup. We applied the same MD methodology to seven additional previously reported STXBP1 mutations and reveal that the stability of the STXBP1-syntaxin 1A interface correlates with the reported clinical phenotypes. This study provides a direct link between the outcome of a novel variant in STXBP1 and protein structure and dynamics. The structural change upon mutation drives an alteration in synaptic function.

Sedaghatian-type spondylometaphyseal dysplasia: Whole exome sequencing in neonatal dry blood spots enabled identification of a novel variant in GPX4.

Accumulation of lipid peroxides causes membrane damage and cell death. Glutathione peroxidase 4 (GPX4) acts as a hydroperoxidase which prevents accumulation of toxic oxidized lipids and blocks ferroptosis, an iron-dependent, non-apoptotic mode of cell death. GPX4 deficiency causes Sedaghatian-type spondylo-metaphyseal dysplasia (SSMD), a lethal autosomal recessive disorder, featuring skeletal dysplasia, cardiac arrhythmia and brain anomalies with only three pathogenic GPX4 variants reported in two SSMD patients. Our objective was to identify the underlying genetic cause of neonatal death of two siblings presenting with hypotonia, cardiorespiratory failure and SSMD. Whole exome sequencing (WES) was performed in DNA samples from two siblings and their parents. Since "critical samples" were not available from the patients, DNA was extracted from dry blood spots (DBS) retrieved from the Israeli newborn-screening center. Sanger sequencing and segregation analysis followed the WES. Homozygous novel GPX4 variant, c.153_160del; p.His52fs*1 causing premature truncation of GPX4 was detected in both siblings; their parents were heterozygotes. Segregation analysis confirmed autosomal recessive inheritance. This report underscores the importance of DBS WES in identifying the genes and mutations causing devastating rare diseases. Obtaining critical samples from a dying patient is crucial for enabling genetic diagnosis.

COG6-CDG: Expanding the phenotype with emphasis on glycosylation defects involved in the causation of male disorders of sex development.

COG6-congenital disorder of glycosylation (COG6-CDG) is caused by biallelic mutations in COG6. To-date, 12 variants causing COG6-CDG in less than 20 patients have been reported. Using whole exome sequencing we identified two siblings with a novel homozygous deletion of 26 bp in COG6, creating a splicing variant (c.518_540 + 3del) and a shift in the reading frame. The phenotype of COG6-CDG includes growth and developmental retardation, microcephaly, liver and gastrointestinal disease, hypohydrosis and recurrent infections. We report two patients with novel phenotypic features including bowel malrotation and ambiguous genitalia, directing attention to the role of glycoprotein metabolism in the causation of disorders of sex development (DSD). Searching the glycomic literature, we identified 14 CDGs including males with DSD, a feature not previously accentuated. This study broadens the genetic and phenotypic spectrum of COG6-CDG and calls for increasing awareness to the central role of glycosylation processes in development of human sex and genitalia.

Genetic counseling of high-risk isolated populations: A worldwide challenge.

BACKGROUND: Isolated populations with high rates of consanguinity and genetic disorders can be found in most parts of the world. The aim of our paper was to highlight the unique challenges faced in genetic counseling for such patients and to discuss the ways to facilitate the difficulties, with an emphasis on the crucial role of electronic medical records (EMR). CASE: We report a couple presenting with elevated maternal alpha-fetoprotein in three pregnancies, in which an erroneous diagnosis of epidermolysis bullosa was established in the past and carried along through several years. The live born proband had no evidence of skin disease; however, soon after birth she was diagnosed with congenital nephrotic syndrome. Sequencing of NPHS1 gene yielded a homozygous likely pathogenic genetic variant c.2104G > A (p.Gly702Arg). Population screening performed in the village of residence revealed a carrier frequency of 1-47. This high frequency justified including testing for the founder genetic variant in the national program for population screening. CONCLUSIONS: Our report highlights the caution, suspicion and time investment which should be practiced and addressed in genetic counseling of high-risk isolated populations. Using EMR may facilitate reaching the correct diagnosis, enable accurate genetic counseling and provide information for decision-making to the couples, as well as "save" a large community from devastating diseases.

A clinically validated whole genome pipeline for structural variant detection and analysis.

BACKGROUND: With the continuing decrease in cost of whole genome sequencing (WGS), we have already approached the point of inflection where WGS testing has become economically feasible, facilitating broader access to the benefits that are helping to define WGS as the new diagnostic standard. WGS provides unique opportunities for detection of structural variants; however, such analyses, despite being recognized by the research community, have not previously made their way into routine clinical practice. RESULTS: We have developed a clinically validated pipeline for highly specific and sensitive detection of structural variants basing on 30X PCR-free WGS. Using a combination of breakpoint analysis of split and discordant reads, and read depth analysis, the pipeline identifies structural variants down to single base pair resolution. False positives are minimized using calculations for loss of heterozygosity and bi-modal heterozygous variant allele frequencies to enhance heterozygous deletion and duplication detection respectively. Compound and potential compound combinations of structural variants and small sequence changes are automatically detected. To facilitate clinical interpretation, identified variants are annotated with phenotype information derived from HGMD Professional and population allele frequencies derived from public and Variantyx allele frequency databases. Single base pair resolution enables easy visual inspection of potentially causal variants using the IGV genome browser as well as easy biochemical validation via PCR. Analytical and clinical sensitivity and specificity of the pipeline has been validated using analysis of Genome in a Bottle reference genomes and known positive samples confirmed by orthogonal sequencing technologies. CONCLUSION: Consistent read depth of PCR-free WGS enables reliable detection of structural variants of any size. Annotation both on gene and variant level allows clinicians to match reported patient phenotype with detected variants and confidently report causative finding in all clinical cases used for validation.

Localized Provoked Vulvodynia: Association With Nerve Growth Factor and Transient Receptor Potential Vanilloid Type 1 Genes Polymorphisms.

OBJECTIVE: The aim of the study was to study the associations between localized provoked vulvodynia (LPV) and several single-nucleotide polymorphisms (SNPs) in the transient receptor potential vanilloid type 1 (TRPV1), nerve growth factor (NGF), and the heparanase (HPSE) genes. MATERIALS AND METHODS: Prevalence of SNPs among 65 women with moderate or severe primary LPV (initial symptoms occur with first provoking physical contact) and 126 healthy, ethnically matched controls was analyzed in an observational case-control study. Each participant answered a questionnaire addressing familial LPV occurrence and comorbid pain conditions. RESULTS: Familial occurrences of LPV, temporomandibular joint (TMJ) symptoms, recurrent vaginitis, and irritable bowel syndrome were significantly higher among LPV women than healthy controls. Genotyping analyses revealed a novel, statistically significant high prevalence of polymorphism c.945G>C (rs222747) of TRPV1 and a SNP in the promoter region of NGF (rs11102930) in LPV women compared with controls. A logistic regression model for rs222747 and rs11102930 frequent alleles indicates significant LPV association within the entire study group and Ashkenazi Jewish women, respectively. Comparison of pain conditions with frequent alleles showed the rs222747 "CC" genotype of TRPV1 associated with women with TMJ, recurrent vaginitis, and LPV. CONCLUSIONS: Our results suggest novel genetic susceptibility to primary LPV associated with specific alleles in genes TRPV1 and NGF and propose the rs222747 "C" allele of TRPV1 as a common genetic predisposition for other pain syndromes.

Two separate functions of NME3 critical for cell survival underlie a neurodegenerative disorder.

We report a patient who presented with congenital hypotonia, hypoventilation, and cerebellar histopathological alterations. Exome analysis revealed a homozygous mutation in the initiation codon of the NME3 gene, which encodes an NDP kinase. The initiation-codon mutation leads to deficiency in NME3 protein expression. NME3 is a mitochondrial outer-membrane protein capable of interacting with MFN1/2, and its depletion causes dysfunction in mitochondrial dynamics. Consistently, the patient's fibroblasts were characterized by a slow rate of mitochondrial dynamics, which was reversed by expression of wild-type or catalytic-dead NME3. Moreover, glucose starvation caused mitochondrial fragmentation and cell death in the patient's cells. The expression of wild-type and catalytic-dead but not oligomerization-attenuated NME3 restored mitochondrial elongation. However, only wild-type NME3 sustained ATP production and viability. Thus, the separate functions of NME3 in mitochondrial fusion and NDP kinase cooperate in metabolic adaptation for cell survival in response to glucose starvation. Given the critical role of mitochondrial dynamics and energy requirements in neuronal development, the homozygous mutation in NME3 is linked to a fatal mitochondrial neurodegenerative disorder.

Pathogenic variants in glutamyl-tRNAGln amidotransferase subunits cause a lethal mitochondrial cardiomyopathy disorder.

Mitochondrial protein synthesis requires charging mt-tRNAs with their cognate amino acids by mitochondrial aminoacyl-tRNA synthetases, with the exception of glutaminyl mt-tRNA (mt-tRNAGln). mt-tRNAGln is indirectly charged by a transamidation reaction involving the GatCAB aminoacyl-tRNA amidotransferase complex. Defects involving the mitochondrial protein synthesis machinery cause a broad spectrum of disorders, with often fatal outcome. Here, we describe nine patients from five families with genetic defects in a GatCAB complex subunit, including QRSL1, GATB, and GATC, each showing a lethal metabolic cardiomyopathy syndrome. Functional studies reveal combined respiratory chain enzyme deficiencies and mitochondrial dysfunction. Aminoacylation of mt-tRNAGln and mitochondrial protein translation are deficient in patients' fibroblasts cultured in the absence of glutamine but restore in high glutamine. Lentiviral rescue experiments and modeling in S. cerevisiae homologs confirm pathogenicity. Our study completes a decade of investigations on mitochondrial aminoacylation disorders, starting with DARS2 and ending with the GatCAB complex.

Newborn screening for cerebrotendinous xanthomatosis is the solution for early identification and treatment.

Cerebrotendinous xanthomatosis (CTX) is a progressive metabolic leukodystrophy. Early identification and treatment from birth onward effectively provides a functional cure, but diagnosis is often delayed. We conducted a pilot study using a two-tier test for CTX to screen archived newborn dried bloodspots (DBSs) or samples collected prospectively from a high-risk Israeli newborn population. All DBS samples were analyzed with flow injection analysis (FIA)-MS/MS, and 5% of samples were analyzed with LC-MS/MS. Consecutively collected samples were analyzed to identify CTX-causing founder genetic variants common among Druze and Moroccan Jewish populations. First-tier analysis with FIA-MS/MS provided 100% sensitivity to detect CTX-positive newborn DBSs, with a low false-positive rate (0.1-0.5%). LC-MS/MS, as a second-tier test, provided 100% sensitivity to detect CTX-positive newborn DBSs with a false-positive rate of 0% (100% specificity). In addition, 5ß-cholestane-3α,7α,12α,25-tetrol-3-O-ß-D-glucuronide was identified as the predominant bile-alcohol disease marker present in CTX-positive newborn DBSs. In newborns identifying as Druze, a 1:30 carriership frequency was determined for the c.355delC CYP27A1 gene variant, providing an estimated disease prevalence of 1:3,600 in this population. These data support the feasibility of two-tier DBS screening for CTX in newborns and set the stage for large-scale prospective pilot studies.

[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.