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ObjectivesWaardenburg syndrome is a rare genetic disorder. It is characterized by sensorineural hearing impairment and pigment defects of the skin, hair and iris. In some cases abnormalities in the tissues derived from neural crest have also been reported. Mutations in several genes have been reported as an underlying cause of Waardenburg syndrome. Objective of this study is to identify the chromosomal region(s) associated with Waardenburg syndrome in an extended Saudi family.MethodsGenomic DNA was extracted from fifteen individuals of a Saudi family segregating Waardenburg syndrome. Whole genome SNP genotyping was performed to identify common identity by descent chromosomal region(s) shared by affected individuals.ResultsPedigree analysis confirm autosomal dominant inheritance of Waardenburg syndrome type II in a family. Whole genome SNP genotypes were analyzed using AutoSNPa and DominantMapper tools. Shared identity by descent chromosomal regions were identified on chromosome 2 and chromosome 18. Regions were checked for known Waardenburg syndrome genes. No known gene is present in both regions.ConclusionsIn summary, we identified novel chromosomal regions associated with Waardenburg syndrome type II in a Saudi family. Deep sequencing of a complete candidate regions are required to identify the gene underlying Waardenburg syndrome in this family.

Waardenburg syndrome (WS) is a hereditary disorder affecting the auditory system and pigmentation of hair, eyes, and skin. Different variants of the disease exist with the involvement of mutation in six genes. The aim of the study is to identify the genetic defects underlying Waardenburg syndrome in a large family with multiple affected individuals. Here, in this study, we recruited a large family with eleven affected individuals segregating WS type 2. We performed whole genome SNP genotyping, whole exome sequencing and segregation analysis using Sanger approach. Whole genome SNP genotyping, whole exome sequencing followed by Sanger validation of variants of interest identified a novel single nucleotide deletion mutation (c.965delA) in the MITF gene. Moreover, a rare heterozygous, missense damaging variant (c.101T>G; p.Val34Gly) in the C2orf74 has also been identified. The C2orf74 is an uncharacterized gene present in the linked region detected by DominantMapper. Variants in MITF and C2orf74 follows autosomal dominant segregation with the phenotype, however, the variant in C2orf74 is incompletely penetrant. We proposed a digenic inheritance of variants as an underlying cause of WS2 in this family.

PurposeTo assess the clinical characteristics of Duane Retraction Syndrome (DRS) in Al-Medina region, in patients attending a pediatric ophthalmology clinic at Ohud Hospital.MethodA cross-sectional observational study was conducted from October 2017 to June 2018 at Ohud Hospital, Al-Medina region, Saudi Arabia. Data was collected using a sheet containing eighteen simple items which include demographic data, family history, surgical history, the clinical characteristics of the disease and the physician's treatment plan. Twenty patients were included in this study.ResultsAll twenty patients included in the study were diagnosed with DRS type I. Male and female were symmetrical in numbers as both 10 (50.0%) respectively. The mean age of the subjects was 8.7 years (SD 9.6). 95% of the subject were unilaterally affected while five percent of them were affected both sides of the eyes. 75% of the patients were affected on the left eye while 20% were affected on the right side. 35% of the patients had amblyopia in the affected eye. 25% of the patients had an abnormal head position. Abnormal eye movement (upshoot and downshoot) more common when the right eye is affected (p-0.035). 75% of the patients were orthotropic while 30% had esotropia. 75% of patients were positive of parents' consanguinity. 16 patients (80.0%) were from Al-Medina city while four of them (20.0%) were from the different area of Al-Medina region (Al Hejeria, Al Henakia, Omluj, Yatmah).ConclusionThis cross-sectional observational study is the first one that evaluates DRS in Al-Medina region. Associated abnormal eye movement more common when the right eye is affected. Parents' consanguinity may play a role in the occurrence of DRS as it is not considered as a rare disease in our region. Therefore, more studies are needed to establish the relationship between the occurrence of DRS and parents' consanguinity in our region. Also, further studies are needed to establish the relationship between abnormal eye movement and the involvement of the right eye.