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Background: Pendred syndrome (PS) and nonsyndromic hearing loss associated with enlarged vestibular aqueduct (EVA) are caused by SLC26A4 mutations. The Okinawa Islands are the southwestern-most islands of the Japanese archipelago. And ancestral differences have been reported between people from Okinawa Island and those from the main islands of Japan. To confirm the ethnic variation of the spectrum of SLC26A4 mutations, we investigated the frequencies of SLC26A4 mutations and clinical manifestations of patients with EVA or PS living in the Okinawa Islands. Methods: We examined 22 patients with EVA or PS from 21 unrelated families in Okinawa Islands. The patient's clinical history, findings of physical and otoscopic examinations, hearing test, and computed tomography (CT) scan of the temporal bones were recorded. To detect mutations, all 21 exons and the exon-intron junctions of SLC26A4 were sequenced for all subjects. Quantitative reverse-transcription polymerase chain reaction (qRT-PCR) for SLC26A4 and calculations using the comparative CT (2-ΔΔCT) method were used to determine the pathogenicity associated with gene substitutions. Results: SLC26A4 mutations were identified in 21 of the 22 patients. We found a compound heterozygous mutation for IVS15 + 5G > A/H723R in nine patients (41%), a homozygous substitution of IVS15 + 5G > A in six patients (27%), and homozygous mutation for H723R in five patients (23%). The most prevalent types of SLC26A4 alleles were IVS15 + 5G > A and H723R, which both accounted for 15/22 (68%) of the patients. There were no significant correlations between the types of SLC26A4 mutation and clinical manifestations. Based on qRT-PCR results, expression of SLC26A4 was not identified in patients with the homozygous substitution of IVS15 + 5G > A. Conclusions: The substitution of IVS15 + 5G > A in SLC26A4 was the most common mutation in uniquely found in patients with PS and EVA in Okinawa Islands. This suggested that the spectrum of SLC26A4 mutation differed from main islands of Japan and other East Asian countries. The substitution of IVS15 + 5G > A leads to a loss of SLC26A expression and results in a phenotype of PS and EVA. [ABSTRACT FROM AUTHOR]

Mutations in the X-linked genes neuroligin 3 (NLGN3) and neuroligin 4X (NLGN4X) were first implicated in the pathogenesis of Xlinked autism in Swedish families. However, reports of mutations in these genes in autism spectrum disorder (ASD) patients from various ethnic backgrounds present conflicting results regarding the etiology of ASD, possibly because of genetic heterogeneity and/or differences in their ethnic background. Additional mutation screening study on another ethnic background could help to clarify the relevance of the genes to ASD.We scanned the entire coding regions of NLGN3 and NLGN4X in 62 Japanese patients with ASD by polymerase chain reaction-high-resolution melting curve and direct sequencing analyses. Four synonymous substitutions, one in NLGN3 and three in NLGN4X, were identified in four of the 62 patients. These substitutions were not present in 278 control X-chromosomes from unrelated Japanese individuals and were not registered in the database of Single Nucleotide Polymorphisms build 132 or in the Japanese Single Nucleotide Polymorphisms database, indicating that they were novel and specific to ASD. Though further analysis is necessary to determine the physiological and clinical importance of such substitutions, the possibility of the relevance of both synonymous and nonsynonymous substitutions with the etiology of ASD should be considered. [ABSTRACT FROM AUTHOR]