Genetic testing for the enlarged vestibular aqueduct syndrome and mutation analysis of the SLC26A4 gene / 中国耳鼻咽喉头颈外科

T,and 916-917 ins G were SLC26A4 mutations unreported hitherto, which may be specific to the Chinese population. CONCLUSION The EVA syndrome is a typical autosomal recessivehereditary disease caused by mutations in SLC26A4 gene. Genetic testing of SLC26A4 is the one of the important diagnostic methods for EVA syndrome.

Screening for mitochondrial DNA mutation in two pedigrees with nonsyndromic inherited sensorineural hearing loss / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To investigate the genetic mechanism of maternal nonsyndromic inherited sensorineural hearing loss(SNHL), to identify the incidence of the 7445(G) mutation in such pedigrees and sporadic patients with SNHL, and to provide the theoretical evidence for the diagnosis of this disease.</p><p><b>METHODS</b>Blood samples were obtained from 2 pedigrees and 14 sporadic patients with SNHL. DNA was extracted from the isolated leukocytes. The mitochondrial DNA (mtDNA) fragments were amplified by PCR. The 1555(G), 3243(G) and 7445(G) mutation was detected by Alw 26 I, Apa I and Xba I restriction endonuclease digestion respectively. The sequence of 12S rRNA, tRNA(Leu(UUR)) and tRNA(Ser(UCN)) was examined.</p><p><b>RESULTS</b>Restriction endonuclease digestion analysis showed that 12 individuals from 2 pedigrees carried homoplasmic 7445(G) mutation, which was of maternal inheritance. Six individuals from 2 pedigrees and 14 sporadic patients did not have 7445(G) mutation. All individuals did not have 1555(G) and 3243(G) mutation. The sequence analysis further showed that none of them carried homoplasmic 1555(G) and 3243(G) mutation, 12 individuals had (nt)7445 A--> G substitution in tRNA(Ser(UCN)) gene.</p><p><b>CONCLUSION</b>The incidence of 7445(G) mutation in such pedigrees is higher than that in sporadic patients. Screening for mtDNA 7445(G) mutation combined with 1555(G) examination is of much value to clinical use.</p>

Detection of mutation in mitochondrial 12S and 16S ribosomal RNA genes in aminoglycoside-induced deafness / 解放军医学杂志

Objective To identify the possible mutations other than A1555G in mitochondrial 12S and 16S rRNA genes that responsible for aminoglycoside-induced deafness, and to provide the basis for genetic diagnosis for this disease. Methods A total of twenty-seven blood samples were obtained from five families with aminoglycoside-induced deafness for screening the A1555G mutation and other possible mutations by PCR- Alw26 I digestion and sequence analysis. Results All samples examined in four families (A, C, D and E) carried the same homoplasmic A1555G mutation, but no A1555G mutation was found in family B. Sequencing of the DNA samples from this family displayed a rare insertion of "AA" at nucleotide 2227 in 16S rRNA gene. Conclusions Our findings suggested that the 1555 G mutation was not the only genetic defect associated with aminoglycoside-induced deafness since we did not find the A1555G mutation in one family, in which the typical maternal inheritance pattern of the aminoglycoside-induced deafness was seen. It is not enough to identify prospectively patients who are likely to be hypersensitive to aminoglycoside ototoxicity by screening A1555G mutation only. Other possible mutations in mitochondrial DNA that associated with aminoglycoside -induced deafness should be tested also.

INVESTIGATION OF A HUGE FAMILY WITH AUTOSOMAL DOMINANT HEREDITARY NON-SYNDROMIC HEARING LOSS / 解放军医学杂志

To investigate a huge family with autosomal dominant hereditary non syndromic hearing loss. In this family, sixty six of 113 family members and 8 spouses have been conducted physical examination, pure tone audiometry, immittance testing and auditory brainstem response testing (ABR). The results indicated that 37 of 66 tested family members have sensorineural hearing loss in various degrees. No associated visible abnormalities in other systems were found in this family. The mode of inheritance of this family should be autosomal dominant according to its pedigree. The full collections of both blood samples and physiological hearing assessments of this family have provided the solid basis for future study on identifying disease causing gene.