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

Clinical Characteristics of Autism Spectrum Disorder in Israel: Impact of Ethnic and Social Diversities

Despite the increased global prevalence and recognition of autistic spectrum disorder (ASD), it is still scarcely reported in the Arab world. Though Israel has a higher prevalence of ASD, a previous national survey of patients diagnosed between 1972 and 2004, demonstrated that 98% of them were of Jewish ancestry. The disproportional low number of Arab children with ASD in Israel is unclear but may reflect lower awareness and cultural bias. In the present study we collected clinical and demographic characteristics of 200 children with ASD from Arab and Jewish sectors in Israel that were evaluated in two child development centers. We compared the incidence and the medical comorbidity of autism between these two ethnics groups. The medical and psychiatric comorbidity profile in these children was similar to the worldwide published studies. In the present study the prevalence of autism in the Arab sector in Israel was similar to that of the Jewish sector. The Arab patients presented with more severe autistic manifestations and higher incidence of mental retardation, familial members with autism, and consanguinity (P<0.05), while in the Jewish sector milder forms (such as Asperger syndrome and PDD-NOS) were more frequent. This discrepancy might be explained by both genetic and cultural factors

Clinical Characteristics of Autism Spectrum Disorder in Israel: Impact of Ethnic and Social Diversities

Despite the increased global prevalence and recognition of autistic spectrum disorder (ASD), it is still scarcely reported in the Arab world. Though Israel has a higher prevalence of ASD, a previous national survey of patients diagnosed between 1972 and 2004, demonstrated that 98% of them were of Jewish ancestry. The disproportional low number of Arab children with ASD in Israel is unclear but may reflect lower awareness and cultural bias. In the present study we collected clinical and demographic characteristics of 200 children with ASD from Arab and Jewish sectors in Israel that were evaluated in two child development centers. We compared the incidence and the medical comorbidity of autism between these two ethnics groups. The medical and psychiatric comorbidity profile in these children was similar to the worldwide published studies. In the present study the prevalence of autism in the Arab sector in Israel was similar to that of the Jewish sector. The Arab patients presented with more severe autistic manifestations and higher incidence of mental retardation, familial members with autism, and consanguinity ( &lt; 0.05), while in the Jewish sector milder forms (such as Asperger syndrome and PDD-NOS) were more frequent. This discrepancy might be explained by both genetic and cultural factors

<i>CLN8</i> 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

CNTNAP1 mutations cause CNS hypomyelination and neuropathy with or without arthrogryposis

To explore the phenotypic spectrum and pathophysiology of human disease deriving from mutations in the gene. In a field study on consanguineous Palestinian families, we identified 3 patients carrying homozygous mutations in the gene using whole-exome sequencing. An unrelated Irish family was detected by screening the GENESIS database for further mutations. Neurophysiology, MRI, and nerve biopsy including electron microscopy were performed for deep phenotyping. We identified 3 novel mutations in 5 patients from 2 families: c.2015G>A:p.(Trp672*) in a homozygous state in family 1 and c.2011C>T:p.(Gln671*) in a compound heterozygous state with c.2290C>T:p.(Arg764Cys) in family 2. Affected patients suffered from a severe CNS disorder with hypomyelinating leukodystrophy and peripheral neuropathy of sensory-motor type. Arthrogryposis was present in 2 patients but absent in 3 patients. Brain MRI demonstrated severe hypomyelination and secondary cerebral and cerebellar atrophy as well as a mega cisterna magna and corpus callosum hypoplasia. Nerve biopsy revealed very distinct features with lack of transverse bands at the paranodes and widened paranodal junctional gaps. mutations have recently been linked to patients with arthrogryposis multiplex congenita. However, we show that arthrogryposis is not an obligate feature. -related disorders are foremost severe hypomyelinating disorders of the CNS and the peripheral nervous system. The pathology is partly explained by the involvement of CNTNAP1 in the proper formation and preservation of paranodal junctions and partly by the assumed role of CNTNAP1 as a key regulator in the development of the cerebral cortex

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

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

International audienceWe 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