Centre for Arab Genomic Studies A Division of Sheikh Hamdan Award for Medical Sciences

The Catalogue for Transmission Genetics in Arabs CTGA Database

Exocyst Complex Component 4

Alternative Names defects. Individuals were diagnosed with MKS EXOC4 based on the presence of occipital encephalocele as SEC8, S. Cerevisiae, Homolog of well as any combination of liver fibrosis, cleft SEC8 palate, dysplastic kidneys, polydactyly and early KIAA1699 lethality. DNA from both affected and healthy members was obtained and an autozygome guided Record Category mutation analysis of known MKS was carried locus out. However, some families did not have mutations in any of the known MKS genes. In such WHO-ICD cases, an exome sequencing was performed. N/A to gene loci Exomes were then searched for compound heterozygous mutations in known MKS genes. Incidence per 100,000 Live Births Failing that, all detected variants were filtered for N/A to gene loci homozygous novel changes within the autozygome. This resulted in the detection of a novel OMIM Number homozygous mutation c.1733A>G (p.Gln578Arg) 608185 in the EXOC4 gene in one of the affected families. This mutation was not found in dbSNP, 1000 Mode of Inheritance genomes or 200 Saudi controls. In-silico analysis N/A to gene loci by PolyPhen predicted this variant to be ‘probably damaging’ while SIFT predicted it to be Gene Map Locus deleterious. The authors noted that EXOC4 had not 7q33 previously been linked to MKS syndrome and that more studies were needed to confirm this Description association. The EXOC4 gene encodes a that forms the exocyst complex along with seven other EXOC References . While not fully characterized in humans, Shaheen R, Faqeih E, Alshammari MJ, Swaid A, the highly conserved protein complex is believed to Al-Gazali L, Mardawi E, Ansari S, Sogaty S, play a key role in protein transport by targeting Seidahmed MZ, AlMotairi MI, Farra C, Kurdi W, exocytic vesicles to specific docking sites on the Al-Rasheed S, Alkuraya FS. Genomic analysis of plasma membrane. The complex is also associated Meckel-Gruber syndrome in Arabs reveals marked with the biogenesis of epithelial cell surface genetic heterogeneity and novel candidate genes. polarity. Eur J Hum Genet. 2013; 21(7):762-8. PMID: 23169490 Molecular Genetics Located on the long arm of 7, the Related CTGA Records EXOC4 gene spans a length of approximately 813 Meckel Syndrome, Type 1 kb and is made up of 24 exons. The protein encoded by this gene is 110 kDa in size and External Links consists of 974 amino acids. Two transcriptional https://www.genecards.org/cgi- splice variants, encoding different isoforms, have bin/carddisp.pl?gene=EXOC4 been characterized. Contributors Epidemiology in the Arab World Sayeeda Hana: 22.8.2016

Saudi Arabia

Shaheen et al. (2013) studied Meckel-Gruber syndrome (MKS) patients from 18 consanguineous Saudi families and identified their underlying gene

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