Molecular Etiology of Hearing Impairment in Inner Mongolia: mutations in SLC26A4 gene and relevant phenotype analysis
The molecular etiology of hearing impairment in Chinese has not been thoroughly investigated. Study of GJB2 gene revealed that 30.4% of the patients with hearing loss in Inner Mongolia carried GJB2 mutations.
The SLC26A4 gene mutations and relevant phenotype are analyzed in this study.
Methods: One hundred and thirty-five deaf patients were included.
The coding exons of SLC26A4 gene were sequence analyzed in 111 patients, not including 22 patients carrying bi-allelic GJB2 mutations or one patient carrying a known GJB2 dominant mutation as well as one patient with mtDNA 1555A>G mutation. All patients with SLC26A4 mutations or variants were subjected to high resolution temporal bone CT scan and those with confirmed enlarged vestibular aqueduct and/or other inner ear malformation were then given further ultrasound scan of thyroid and thyroid hormone assays.
Results: Twenty-six patients (19.26%, 26/135) were found carrying SLC26A4 mutation, of whom 17 patients with bi-allelic SLC26A4 mutations or variants were all confirmed to have EVA or other inner ear malformation by CT scan. Nine patients were heterozygous for one SLC26A4 mutation, of whom 3 were confirmed to be EVA or EVA and Mondini dysplasia by CT scan.
IVS7-2A>G, the most common, accounted for 58.14% (25/43) of all SLC26A4 mutant alleles. The shape and function of thyroid were confirmed to be normal by thyroid ultrasound scan and thyroid hormone assays in 19 of the 20 patients with EVA or other inner ear malformation except one who had cystoid change in the right side of thyroid.
No Pendred syndrome was diagnosed.
Conclusions: In Inner Mongolia, China, mutations in SLC26A4 gene account for about 14.81% (20/135) of the patients with hearing loss.
SLC26A4 is the second common gene next to GJB2 that cause deafness in this area. Pendred syndrome seems not to be common in Inner Mongolia.
We established a new strategy that detects SLC26A4 mutations prior to the temporal bone CT scan to find EVA and inner ear malformation patients. This model has unique advantage in epidemiologic study in large-scale deaf population.
Author: Pu Dai, Yongyi Yuan, Deliang Huang, Xiuhui Zhu, Fei Yu, Dongyang Kang, Huijun Yuan, Bailin Wu, Dongyi Han and Lee-Jun C. Wong
Credits/Source: Journal of Translational Medicine 2008, 6:74
Published on: 2008-12-01
Copyright by the authors listed above - made available via BioMedCentral (Open Access). Please
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