The prevailing trend of consanguinity in the Arab society of Israel: is it still a challenge?

The aim of this study was to determine the trend of consanguineous marriage among the Arab population in Israel. Socio-demographic data for the Arab population were extracted from national health surveys conducted in Israel in 2007 and 2017. The prevalence of consanguineous marriage among the Arab population in Israel increased significantly from 36.3% to 41.6% in the decade from 2007 to 2017. First-cousin and closer marriages constituted about 50% of total consanguineous marriages in the two periods surveyed. Consanguinity was found to be significantly related to religion and place of residence. Thus, the prevalence of consanguineous marriage remains high among the Arab population in Israel, similar to other Arab societies. These findings affect the health of future generations and impose a challenge for health care professionals.

Multidomain Cognitive Impairment in Children With Pseudotumor Cerebri Syndrome.

BACKGROUND: Although prompt and suitable treatment of pseudotumor cerebri syndrome (PTCS) leads to an excellent prognosis and can prevent optic nerve atrophy, adults show long-lasting neurocognitive deficits even with prompt treatment. The purpose of our study was to evaluate cognitive outcomes in pediatric patients with PTCS. METHODS: We performed a prospective study on children diagnosed with PTCS and a healthy control group. Children with pre-existing neurological conditions or psychiatric drug use were excluded. Both groups underwent a neurocognitive evaluation, using the NeuroTrax computerized battery of tests. The PTCS group were tested 3 months after the initial diagnosis. RESULTS: We evaluated 82 children (49 females [60%], 6.5-16 years old, mean age 13.3), including 26 diagnosed with idiopathic PTC and 56 controls. Global cognitive score (P < 0.001), verbal memory (P < 0.001), executive function (P < 0.001), attention (P< 0.003), and information processing speed (P < 0.004) were all significantly lower in the PTCS group. No differences were found between children currently being treated and those whose symptoms had resolved and treatment was stopped. CONCLUSIONS: Children with PTCS experience comprehensive cognitive decline that persists after the resolution of the symptoms and treatment.

Homozygous stop mutation in AHR causes autosomal recessive foveal hypoplasia and infantile nystagmus.

Herein we present a consanguineous family with three children affected by foveal hypoplasia with infantile nystagmus, following an autosomal recessive mode of inheritance. The patients showed normal electroretinography responses, no signs of albinism, and no anterior segment or brain abnormalities. Upon whole exome sequencing, we identified a homozygous mutation (c.1861C>T;p.Q621*) in the aryl hydrocarbon receptor (AHR) gene that perfectly co-segregated with the disease in the larger family. AHR is a ligand-activated transcription factor that has been intensively studied in xenobiotic-induced toxicity. Further, it has been shown to play a physiological role under normal cellular conditions, such as in immunity, inflammatory response and neurogenesis. Notably, knockout of the Ahr gene in mouse impairs optic nerve myelin sheath formation and results in oculomotor deficits sharing many features with our patients: the eye movement disorder in Ahr-/- mice appears early in development and presents as conjugate horizontal pendular nystagmus. We therefore propose AHR to be a novel disease gene for a new, recessively inherited disorder in humans, characterized by infantile nystagmus and foveal hypoplasia.

A novel biallelic loss-of-function mutation in TMCO1 gene confirming and expanding the phenotype spectrum of cerebro-facio-thoracic dysplasia.

The main clinical features of cerebro-facio-thoracic dysplasia (CFTD) syndrome, which were described over four decades ago, include facial dysmorphism, multiple malformations of the vertebrae and ribs, and intellectual disability. Recently, a TMCO1 gene mutation was shown to be responsible for an autosomal recessive CFTD syndrome characterized by craniofacial dysmorphism, skeletal anomalies, and intellectual disability. In the current report, we describe two members of a consanguineous family from an Arab community in Israel who were clinically diagnosed as suffering from craniofacial dysmorphism, skeletal anomalies, intellectual disability, and epilepsy. Both affected siblings had behavioral difficulties such as anxiety and emotional instability with impulsive behaviors. Whole-exome sequencing revealed a homozygous stop-gain mutation NM_019026.4: c.616C > T; p.(Arg206*) in exon 6 of the TMCO1 gene. Bioinformatics analysis suggested a structural model for the TMCO1 protein and its homologues. The clinical features of our patients were compared with those of the only other five studies available in the literature. We conclude that this mutation in the TMCO1 gene is responsible for the various clinical manifestations of CFTD syndrome exhibited by the patients studied that expand the phenotypic spectrum of the disease to include epilepsy as a characteristic feature of this syndrome.

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.

Hypomorphic mutations in POLR3A are a frequent cause of sporadic and recessive spastic ataxia.

Despite extensive efforts, half of patients with rare movement disorders such as hereditary spastic paraplegias and cerebellar ataxias remain genetically unexplained, implicating novel genes and unrecognized mutations in known genes. Non-coding DNA variants are suspected to account for a substantial part of undiscovered causes of rare diseases. Here we identified mutations located deep in introns of POLR3A to be a frequent cause of hereditary spastic paraplegia and cerebellar ataxia. First, whole-exome sequencing findings in a recessive spastic ataxia family turned our attention to intronic variants in POLR3A, a gene previously associated with hypomyelinating leukodystrophy type 7. Next, we screened a cohort of hereditary spastic paraplegia and cerebellar ataxia cases (n = 618) for mutations in POLR3A and identified compound heterozygous POLR3A mutations in ∼3.1% of index cases. Interestingly, >80% of POLR3A mutation carriers presented the same deep-intronic mutation (c.1909+22G>A), which activates a cryptic splice site in a tissue and stage of development-specific manner and leads to a novel distinct and uniform phenotype. The phenotype is characterized by adolescent-onset progressive spastic ataxia with frequent occurrence of tremor, involvement of the central sensory tracts and dental problems (hypodontia, early onset of severe and aggressive periodontal disease). Instead of the typical hypomyelination magnetic resonance imaging pattern associated with classical POLR3A mutations, cases carrying c.1909+22G>A demonstrated hyperintensities along the superior cerebellar peduncles. These hyperintensities may represent the structural correlate to the cerebellar symptoms observed in these patients. The associated c.1909+22G>A variant was significantly enriched in 1139 cases with spastic ataxia-related phenotypes as compared to unrelated neurological and non-neurological phenotypes and healthy controls (P = 1.3 × 10-4). In this study we demonstrate that (i) autosomal-recessive mutations in POLR3A are a frequent cause of hereditary spastic ataxias, accounting for about 3% of hitherto genetically unclassified autosomal recessive and sporadic cases; and (ii) hypomyelination is frequently absent in POLR3A-related syndromes, especially when intronic mutations are present, and thus can no longer be considered as the unifying feature of POLR3A disease. Furthermore, our results demonstrate that substantial progress in revealing the causes of Mendelian diseases can be made by exploring the non-coding sequences of the human genome.

Homozygous mutation in PTRH2 gene causes progressive sensorineural deafness and peripheral neuropathy.

PTRH2 is an evolutionarily highly conserved mitochondrial protein that belongs to a family of peptidyl-tRNA hydrolases. Recently, patients from two consanguineous families with mutations in the PTRH2 gene were reported. Global developmental delay associated with microcephaly, growth retardation, progressive ataxia, distal muscle weakness with ankle contractures, demyelinating sensorimotor neuropathy, and sensorineural hearing loss were present in all patients, while facial dysmorphism with widely spaced eyes, exotropia, thin upper lip, proximally placed thumbs, and deformities of the fingers and toes were present in some individuals. Here, we report a new family with three siblings affected by sensorineural hearing loss and peripheral neuropathy. Autozygosity mapping followed by exome sequencing identified a previously reported homozygous missense mutation in PTRH2 (c.254A>C; p.(Gln85Pro)). Sanger sequencing confirmed that the variant segregated with the phenotype. In contrast to the previously reported patient, the affected siblings had normal intelligence, milder microcephaly, delayed puberty, myopia, and moderate insensitivity to pain. Our findings expand the clinical phenotype and further demonstrate the clinical heterogeneity related to PTRH2 variants.

CHANGES IN MARRIAGE PATTERNS AMONG THE ARAB COMMUNITY IN ISRAEL OVER A 60-YEAR PERIOD.

The aim of this study was to determine the prevalence and trends of various types of consanguineous marriage among the Arab community in Israel over a long time period (1948-2007) by religion and educational level. Data were collected by face-to-face interview of 3173 Arab couples living in Israel in 2007 and 2008. The trend in consanguineous marriages was found to decrease significantly over successive time periods, from 42.5% to 30.9% (p=0.001), and the prevalence of first-cousin and closer marriages decreased, from 23% to 12.7%. Consanguinity was found to be significantly related to religion (p=0.001) and wife's level of education (p=0.028).

Clinical Profile of Attention Deficit Hyperactivity Disorder: Impact of Ethnic and Social Diversities in Israel.

BACKGROUND: Despite the increased worldwide recognition of attention deficit/hyperactivity disorder (ADHD), there is a variability in the diagnostic rate of both ADHD and its co-morbidities. These diversities are probably related to the methodology and instruments used for the diagnosis of ADHD and to awareness and cultural interpretation of its existence. OBJECTIVES: To identify consistent differences in the clinical profile of Arab and Jewish children with ADHD in Israel who differ in cultural, ethnic and socioeconomic background. METHODS: We analyzed the data of 823 children and adolescents with ADHD (516 Jews and 307 Arabs) and compared the clinical characteristics between these two ethnic groups. All patients were evaluated in two neuropediatric and child development centers in northern Israel: one in Haifa and one in Hadera. Children with autism and intellectual disabilities were excluded. RESULTS: The distribution of ADHD subtypes was similar in both populations. However, learning disorders and psychiatric co-morbidities (behavioral difficulties and anxiety) were reported more frequently in the Jewish population. The most commonly reported adverse effects to psychostimulants were mood changes, anorexia, headache, insomnia and rebound effect, and were more frequently reported in the Jewish population (42.0% vs.18.0%, P < 0.05). CONCLUSIONS: We assume that these differences are related to cultural and socioeconomic factors. We suggest that the physician take cultural background into consideration when treating patients with ADHD.

Novel homozygous large deletion including the 5' part of the SPATA7 gene in a consanguineous Israeli Muslim Arab family.

PURPOSE: To identify the genetic defect in a consanguineous Israeli Muslim Arab family with juvenile retinitis pigmentosa (RP). METHODS: DNA samples were collected from the index patient, her parents, her affected sister, and two non-affected siblings. Genome-wide linkage analysis with 250 K single nucleotide polymorphism (SNP) arrays was performed using DNA from the two affected patients. Owing to consanguinity in the family, we applied homozygosity mapping to identify the disease-causing gene. The candidate gene SPATA7 was screened for mutations with PCR amplifications and direct Sanger sequencing. RESULTS: Following high-density SNP arrays, we identified several homozygous genomic regions one of which included the SPATA7 gene. Several mutations in SPATA7 have been reported for various forms of retinal dystrophy, including Leber congenital amaurosis (LCA) and juvenile RP. PCR-based sequence content mapping, long-distance PCR amplifications, and subsequent sequencing analysis revealed a homozygous 63.4 kb large deletion that encompasses the 5' part of the SPATA7 gene including exons 1-5. The mutation showed concordant segregation with the phenotype in the family as expected for autosomal recessive mode of inheritance and is consistent with a diagnosis of juvenile RP. CONCLUSIONS: We report a novel homozygous large deletion in SPATA7 associated with juvenile RP in a consanguineous Israeli Muslim Arab family. This is the first larger deletion mutation reported for SPATA7.

The tumour suppressor gene WWOX is mutated in autosomal recessive cerebellar ataxia with epilepsy and mental retardation.

We previously localized a new form of recessive ataxia with generalized tonic-clonic epilepsy and mental retardation to a 19 Mb interval in 16q21-q23 by homozygosity mapping of a large consanguineous Saudi Arabian family. We now report the identification by whole exome sequencing of the missense mutation changing proline 47 into threonine in the first WW domain of the WW domain containing oxidoreductase gene, WWOX, located in the linkage interval. Proline 47 is a highly conserved residue that is part of the WW motif consensus sequence and is part of the hydrophobic core that stabilizes the WW fold. We demonstrate that proline 47 is a key amino acid essential for maintaining the WWOX protein fully functional, with its mutation into a threonine resulting in a loss of peptide interaction for the first WW domain. We also identified another highly conserved homozygous WWOX mutation changing glycine 372 to arginine in a second consanguineous family. The phenotype closely resembled the index family, presenting with generalized tonic-clonic epilepsy, mental retardation and ataxia, but also included prominent upper motor neuron disease. Moreover, we observed that the short-lived Wwox knock-out mouse display spontaneous and audiogenic seizures, a phenotype previously observed in the spontaneous Wwox mutant rat presenting with ataxia and epilepsy, indicating that homozygous WWOX mutations in different species causes cerebellar ataxia associated with epilepsy.

Factors affecting the utilization of genetic counseling services among Israeli Arab women.

OBJECTIVES: To assess the factors associated with utilization of genetic counseling services among pregnant Israeli Arab women. METHODS: A case-control study was conducted among 414 pregnant Arab women who were referred by a family physician or a perinatologist to genetic counseling services between 2008 and 2011. Data was collected using interviews, with both groups 'users' and 'non-users' of genetic counseling, based on a structured questionnaire including demographic, socio-economic, medical and cultural variables. RESULTS: In multivariate analysis, factors affecting women's utilization of genetic counseling service were high income level (OR 3.44, 95%CI 1.8-6.5, p < 0.001), high service accessibility (OR 0.75, 95%CI 0.67-0.84, p = 0.001), more positive attitude toward genetic counseling (OR 0.43, 95%CI 0.27-0.67, p = 0.012) and lower religiosity level (OR 1.40, 95%CI 0.94-2.09, p = 0.04). However, when we examined the following variable: pregnant woman's age, woman's education, consanguinity and pregnancy' age, knowledge level and the perspective toward abortion, no significant differences were found between the users and non-users groups. CONCLUSIONS: The underutilization of genetic counseling services among pregnant Israeli Arab women was associated with the following: lower income level, attitude toward genetic counseling, accessibility to service and religiosity. Thus, it is advisable to expand genetic counseling service within this community. © 2014 John Wiley & Sons, Ltd.

SCAPER-Related Autosomal Recessive Retinitis Pigmentosa with Intellectual Disability: Confirming and Extending the Phenotypic Spectrum and Bioinformatics Analyses.

Mutations in the gene SCAPER (S phase Cyclin A-Associated Protein residing in the Endoplasmic Reticulum) have recently been associated with retinitis pigmentosa (RP) and intellectual disability (ID). In 2011, a possible involvement of SCAPER in human diseases was discovered for the first time due to the identification of a homozygous mutation causing ID in an Iranian family. Later, five studies were published in 2019 that described patients with autosomal recessive syndromic retinitis pigmentosa (arRP) accompanied by ID and attention-deficit/hyperactivity disorder (ADHD). This present study describes three patients from an Arab consanguineous family in Israel with similar clinical features of the SCAPER syndrome. In addition, new manifestations of ocular symptoms, nystagmus, glaucoma, and elevator palsy, were observed. Genetic testing of the patients and both parents via whole-exome sequencing revealed the homozygous mutation c.2023-2A>G in SCAPER. Phenotypic and genotypic descriptions for all available cases described in the literature including our current three cases (37 cases) were carried out, in addition to a bioinformatics analysis for all the genetic variants that was undertaken. Our study confirms and extends the clinical manifestations of SCAPER-related disorders.

PTRH2 Gene Variants: Recent Review of the Phenotypic Features and Their Bioinformatics Analysis.

Peptidyl-tRNA hydrolase 2 (PTRH2) is an evolutionarily highly conserved mitochondrial protein. The biallelic mutations in the PTRH2 gene have been suggested to cause a rare autosomal recessive disorder characterized by an infantile-onset multisystem neurologic endocrine and pancreatic disease (IMNEPD). Patients with IMNEPD present varying clinical manifestations, including global developmental delay associated with microcephaly, growth retardation, progressive ataxia, distal muscle weakness with ankle contractures, demyelinating sensorimotor neuropathy, sensorineural hearing loss, and abnormalities of thyroid, pancreas, and liver. In the current study, we conducted an extensive literature review with an emphasis on the variable clinical spectrum and genotypes in patients. Additionally, we reported on a new case with a previously documented mutation. A bioinformatics analysis of the various PTRH2 gene variants was also carried out from a structural perspective. It appears that the most common clinical characteristics among all patients include motor delay (92%), neuropathy (90%), distal weakness (86.4%), intellectual disability (84%), hearing impairment (80%), ataxia (79%), and deformity of head and face (~70%). The less common characteristics include hand deformity (64%), cerebellar atrophy/hypoplasia (47%), and pancreatic abnormality (35%), while the least common appear to be diabetes mellitus (~30%), liver abnormality (~22%), and hypothyroidism (16%). Three missense mutations were revealed in the PTRH2 gene, the most common one being Q85P, which was shared by four different Arab communities and was presented in our new case. Moreover, four different nonsense mutations in the PTRH2 gene were detected. It may be concluded that disease severity depends on the PTRH2 gene variant, as most of the clinical features are manifested by nonsense mutations, while only the common features are presented by missense mutations. A bioinformatics analysis of the various PTRH2 gene variants also suggested the mutations to be deleterious, as they seem to disrupt the structural confirmation of the enzyme, leading to loss of stability and functionality.

High CCL2 Levels Detected in CSF of Patients with Pediatric Pseudotumor Cerebri Syndrome.

Pseudotumor cerebri (PTC) is a disorder characterized by increased intracranial pressure in the absence of a structural lesion or other identifiable cause. Cytokines, which are involved in the regulation of immune responses and inflammation, have been implicated in the pathogenesis of PTC. In a prospective, cross-sectional study at three centers in Israel, we analyzed cerebrospinal fluid (CSF) samples from 60 children aged 0.5-18 years, including 43 children with a definitive diagnosis of PTC and a control group of 17 children. Levels of IL-4, IL-10, IL-17, CCL2, CCL7, CCL8, CCL13, BDNF, and IFN-γ were measured using ELISA kits. Levels of CCL2 were significantly higher in the PTC group compared to the control group (p < 0.05), with no other significant differences in the measured cytokines between the two groups. The groups did not differ significantly in clinical presentation, imaging, treatment, or ophthalmic findings. Our findings provide preliminary evidence that CCL2 may be involved in the pathogenesis of PTC and may serve a potential target for therapy in PTC.

CLN8 Gene Compound Heterozygous Variants: A New Case and Protein Bioinformatics Analyses.

The CLN8 disease type refers to one of the neuronal ceroid lipofuscinoses (NCLs) which are the most common group of neurodegenerative diseases in childhood. The clinical phenotypes of this disease are progressive neurological deterioration that could lead to seizures, dementia, ataxia, visual failure, and various forms of abnormal movement. In the current study, we describe two patients who presented with atypical phenotypic manifestation and protracted clinical course of CLN8 carrying a novel compound heterozygous variant at the CLN8 gene. Our patients developed a mild phenotype of CLN8 disease: as they presented mild epilepsy, cognitive decline, mild learning disability, attention-deficit/hyperactivity disorder (ADHD), they developed a markedly protracted course of motor decline. Bioinformatic analyses of the compound heterozygous CLN8 gene variants were carried out. Most of the variants seem likely to act by compromising the structural integrity of regions within the protein. This in turn is expected to reduce the overall stability of the protein and render the protein less active to various degrees. The cases in our study confirmed and expanded the effect of compound heterozygous variants in CLN8 disease.

The Current and Forecasted Status of Type 2 Diabetes in the Arab Society of Israel.

BACKGROUND: Diabetes mellitus (DM) is considered one of the main causes of mortality, morbidity, and health care expenditures. Effectively treating this disease is of crucial importance and imposes a global challenge. The incidence of Type 2 DM (T2DM) is rapidly rising in both developing and developed countries. The Arab community in Israel is a distinct ethnic group with unique characteristics. Recently, this community has undergone major changes in its lifestyle, adopting the Westernized one, which could have caused an increase in the T2DM incidence rate. OBJECTIVE: This review aims to shed light on various studies undertaken to explore the prevalence of diabetes and determine its current status in the Arab society of Israel, resting on previous and current data. It is presented to highlight the status of diabetes globally and to focus on its current situation in the Arab society of Israel, attempting to forecast its direction in the upcoming decade. METHODS: Data were obtained from our previous comprehensive socio-economic and health crosssectional surveys for successive periods from 2004 to 2017. These surveys were conducted on the Arab society of Israel by the Galilee Society. RESULTS: Our results showed a progressive increase in the prevalence of T2DM from 3.4% to 7.6% in the Arab society of Israel. This trend is expected to continue rising in the coming decade, and based on our predictions, may exceed 12% in 2030. CONCLUSION: Substantial and practical health-related actions must be initiated to prevent an increasing number of adults from developing diabetes and its complications.

The Clinical Characteristics of ADHD Diagnosed in Adolescents in Comparison With Younger Children.

Objective: The aim of this study is to identify the clinical characteristics in adolescents newly diagnosed with ADHD. Method: Data of patients aged 7 to 17 years diagnosed with ADHD were collected and analyzed. The patients were divided into adolescents aged 13 to 17 years (Group I) and children aged 7 to 12 years (Group II): 592 males and 231 females. Group I consists of 450 participants, and Group II consists of 373 participants. Results: Adolescents were predominantly inattentive (63.8%); most of Group II patients had combined or hyperactive ADHD (70.8%). Learning disorders were more common in adolescents (51.2% vs. 39.7%) and treated mainly with long-acting methylphenidate (MPH), and Group II patients were treated mainly with short- and medium-acting MPH. Newly diagnosed adolescents were less likely to exhibit behavioral comorbidities. Headache and insomnia were reported more in adolescents, and stimulant rebound effect was more in younger children. Conclusion: Although the biological nature of ADHD is similar in both age groups, the primary symptomatology and associated comorbidities are prone to age-dependent changes.

Gene and Protein Expression in Subjects With a Nystagmus-Associated AHR Mutation.

Recently, a consanguineous family was identified in Israel with three children affected by Infantile Nystagmus and Foveal Hypoplasia, following an autosomal recessive mode of inheritance. A homozygous stop mutation c.1861C > T; p.Q621∗ in the aryl hydrocarbon receptor (AHR) gene (AHR; MIM 600253) was identified that co-segregated with the disease in the larger family. AHR is the first gene to be identified causing an autosomal recessive Infantile Nystagmus-related disease in humans. The goal of this study is to delineate the molecular basis of this newly discovered human genetic disorder associated with a rare AHR gene mutation. The gene and protein expression levels of AHR and selected AHR targets from leukocyte cultures of healthy subjects and the patients were analyzed. We observed significant variation between mRNA and protein expression of CYP1A1, CYP1B1, and TiPARP under rest and AHR-induced conditions. The CYP1A1 enzymatic activity in induced leukocytes also differs significantly between the patients and healthy volunteers. Intriguingly, the heterozygous subjects demonstrate CYP1A1 and TiPARP gene and protein expression similar to homozygous patients. In contrast, CYP1B1 inducibility and expression vary between hetero- and homozygous subjects. Similarity and differences in gene and protein expression between heterozygotes and homozygous patients can give us a hint as to which metabolic pathway/s might be involved in the Nystagmus etiology. Thus, we have a unique human model for AHR deficiency that will allow us the opportunity to study the biochemical basis of this rare human mutation, as well as the involvement of AHR in other physiological processes.

Unraveling the genetic cause of hereditary ophthalmic disorders in Arab societies from Israel and the Palestinian Authority.

Visual impairment due to inherited ophthalmic disorders is amongst the most common disabilities observed in populations practicing consanguineous marriages. Here we investigated the molecular genetic basis of an unselected broad range of ophthalmic disorders in 20 consanguineous families from Arab villages of Israel and the Palestinian Authority. Most patients had little or very poor prior clinical workup and were recruited in a field study. Homozygosity mapping followed by candidate gene sequencing applying conventional Sanger sequencing or targeted next generation sequencing was performed in six families. In the remaining 14 families, one affected subject per family was chosen for whole exome sequencing. We discovered likely disease-causing variants, all homozygous, in 19 of 20 independent families (95%) including a previously reported novel disease gene for congenital nystagmus associated with foveal hypoplasia. Moreover, we found a family in which disease-causing variants for two collagenopathies - Stickler and Knobloch syndrome - segregate within a large sibship. Nine of the 19 distinct variants observed in this study were novel. Our study demonstrated a very high molecular diagnostic yield for a highly diverse spectrum of rare ophthalmic disorders in Arab patients from Israel and the Palestinian Authority, even with very limited prior clinical investigation. We conclude that 'genetic testing first' may be an economic way to direct clinical care and to support proper genetic counseling and risk assessment in these families.