Real-time Taqman probe technique system for detecting the MtDNA 1555 A > G mutation / 中华耳鼻咽喉头颈外科杂志

<p><b>OBJECTIVE</b>To establish a Real-time Taqman probe technique system to detect the mtDNA 1555A > G mutation in deaf population.</p><p><b>METHODS</b>Primers and Taqman probes for mtDNA 1555A > G mutation were designed and synthesized. The technique system for detecting mtDNA 1555A > G mutation using Real-time Taqman probes was established. Then the reliability of the technique was tested in 132 patients with severe to profound hearing loss who were detected for the mtDNA 1555A > G mutation by sequencing, Kit method and Real-time Taqman probe technique at the same time. Finally, the results by the above three ways were compared.</p><p><b>RESULTS</b>Thirty-two cases with mtDNA 1555A > G mutation were found by the technique of Real-time Taqman probe. These findings coincided with the results from sequencing and Kit method completely. Both the false positive rate and the false negative rate were zero.</p><p><b>CONCLUSIONS</b>The technique possesses the merits of accuracy, convenience, high sensitivity, high specificity and intuitionistic results, etc. Importantly, the Real-time Taqman probe technique only needs 1.5 hours to detect the 1555A > G mutation and it saves 4.5 hours for one reaction compared with the Kit method popularly used nowadays. The technique system of detecting mtDNA 1555A > G mutation is reliable. It's suitable for large-scale detecting and preventive diagnosis of mtDNA 1555A > G mutation.</p>

Frequency of SLC26A4 IVS7-2A > G mutation in patients with severe to profound hearing loss from different area and ethnic group in China / 中华耳鼻咽喉头颈外科杂志

<p><b>OBJECTIVE</b>To carry out molecular epidemiology study of SLC26A4 IVS7-2 A > G mutation in large Chinese deaf population and to provide evidence for fast screening and gene diagnosis of enlarged vestibular aqueduct syndrome (EVAS).</p><p><b>METHODS</b>A total of 1979 patients with non-syndromic hearing loss(NSHL) underwent questionnaire and PCR for IVSA > G mutation detection of SLC26A4 gene.</p><p><b>RESULTS</b>All 245 patients (12.38%) with homozygotes and heterozygotes IVS7-2 A > G mutation were found among the 1979 NSHL It showed statistically significant difference among north and northeast, northwest, east and southeast, southwest and central area in China. (chi2 = 34.4899, P < 0.05). Carrier frequency of the central area (27.52%) was notably higher than southwest area (6.69%). The IVS7-2 A > G mutation was most frequently found in Han deaf groups (13.88%). Tibetan, Hui, and other western minorities were lower than Han deaf population (chi2 = 35.4456, P < 0.05).</p><p><b>CONCLUSIONS</b>A high SLC26A4 IVS7-2 A > G mutation frequency for deafness in Chinese patients was found. Detection of the pathogenic mutations was bringing the possibility to detect EVAS at an early stage. Moreover, it might help to establish diverse diagnostic strategies toward differently ethical deaf population in different region of China.</p>

Genetic counseling and instruction for deaf couples directed by genetic testing / 中华耳鼻咽喉头颈外科杂志

<p><b>OBJECTIVE</b>To analyze the molecular pathogenesis of deaf couples by means of genetic testing. To provide accurate genetic counseling and instruction for deaf couples with different etiology based upon results of genetic testing.</p><p><b>METHODS</b>Four deaf families from July 2005 to May 2006. Each subject was with moderate to profound hearing loss. Genomic and mitochondrial DNA (mtDNA) of each subject were extracted from whole blood. Genetic testing of GJB2, SLC26A4 (PDS) and mtDNA A1555G mutation were offered to each individuals.</p><p><b>RESULTS</b>The husband from family 1 didn't carry GJB2, SLC26A4 and mtDNA A1555G mutation while his wife was confirmed to carry compound SLC26A4 mutations. The possibility of their offspring's to be SLC26A4 single mutation carrier was 100%. The couple from family 2 both didn't carry GJB2, SLC26A4 and mtDNA A1555G mutation. The possibility of their offspring's having hereditary deafness caused by GJB2, SLC26A4 and mtDNA A1555G mutation was excluded. The husband from family 3 was confirmed to carry homozygous GJB2 mutations and a single SLC26A4 mutation while his wife who was diagnosed with enlarged vestibular aqueduct syndrome (EVAS) by CT scan was proven to carry a single SLC26A4 mutation. The risk of their offspring's suffering EVAS was 50%. The husband from family 4 was mtDNA A1555G positive while his wife who was diagnosed with cochlear malformation by CT scan didn't carry GJB2, SLC26A4 and mtDNA A1555G mutation. The risk of their offspring's having hereditary deafness caused by GJB2, SLC26A4 and mtDNA A1555G mutation was excluded.</p><p><b>CONCLUSIONS</b>Genetic testing could be applied to offer the more accurate genetic counseling and instruction to deaf couples.</p>