Analysis of GJB2 gene coding sequence in patients with nonsyndromic hearing loss / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To analyze the coding sequence of GJB2 gene in six pedigrees with nonsyndromic hearing loss in order to find deafness-causing mutations in the GJB2 gene, and to explore the inherent pattern of deafness-causing mutations in the GJB2 gene.</p><p><b>METHODS</b>Genomic DNA was extracted from peripheral blood for the probands and their family members. Coding sequence of the GJB2 gene was amplified by polymerase chain reaction, sequence variations were determined by DNA sequencing. Amplified fragments with overlapping peaks on sequencing chromatogram were sequenced by TA cloning in order to determine whether the mutations originated from the same allele.</p><p><b>RESULTS</b>Mutations in the GJB2 gene were found in 4 out of the 6 pedigrees with nonsyndromic hearing loss. Four types of mutations were detected in the GJB2 gene, which were 235delC, 299-300delAT, 79G>A+341A>G, and 109G>A. Compound heterozygous polymorphisms 79G>A and 341A>G, and mutations 109G>A and 235delC had deafness-causing effects.</p><p><b>CONCLUSION</b>Heterogeneous mutations of the GJB2 gene are frequently seen in patients with nonsyndromic hearing loss. Sometimes, polymorphisms may cause deafness when they are combined. Environmental factors and other genes may contribute to hearing loss caused by the GJB2 gene mutations.</p>

Mutation of thyroid peroxidase gene in 35 patients with congenital hypothyroidism / 中华儿科杂志

<p><b>OBJECTIVE</b>To identify thyroid peroxidase (TPO) gene mutations in 35 patients with congenital hypothyroidism.</p><p><b>METHOD</b>Genomic DNA was isolated from peripheral blood samples of 35 patients with congenital hypothyroidism. All of the 17 exons and flanking introns of TPO gene were amplified by PCR, then the PCR products were sequenced bi-directionally and were analyzed by restriction endonucleases.</p><p><b>RESULT</b>One patient had compound heterozygous mutations c.961A>G/c.2422delT, one was c.2268insT/c.1477G>A, and three was homozygous mutation c.2268insT. The TPO gene mutation c.961A>G [p. Thr321Ala] was one novel mutation.</p><p><b>CONCLUSION</b>High frequency mutation in TPO gene was detected in patients with congenital hypothyroidism.</p>