GJB2 Mutation Spectrum and Genotype-Phenotype Correlation in 1067 Han Chinese Subjects with Non-Syndromic Hearing Loss.

Mutations in Gap Junction Beta 2 (GJB2) have been reported to be a major cause of non-syndromic hearing loss in many populations worldwide. The spectrums and frequencies of GJB2 variants vary substantially among different ethnic groups, and the genotypes among these populations remain poorly understood. In the present study, we carried out a systematic and extended mutational screening of GJB2 gene in 1067 Han Chinese subjects with non-syndromic hearing loss, and the resultant GJB2 variants were evaluated by phylogenetic, structural and bioinformatic analysis. A total of 25 (23 known and 2 novel) GJB2 variants were identified, including 6 frameshift mutations, 1 nonsense mutation, 16 missense mutations and 2 silent mutations. In this cohort, c.235delC is the most frequently observed pathogenic mutation. The phylogenetic, structural and bioinformatic analysis showed that 2 novel variants c.127G>T (p.V43L), c.293G>C (p.R98P) and 2 known variants c. 107T>C (p.L36P) and c.187G>T (p.V63L) are localized at highly conserved amino acids. In addition, these 4 mutations are absent in 203 healthy individuals, therefore, they are probably the most likely candidate pathogenic mutations. In addition, 66 (24 novel and 42 known) genotypes were identified, including 6 homozygotes, 20 compound heterozygotes, 18 single heterozygotes, 21 genotypes harboring only polymorphism(s) and the wild type genotype. Among these, 153 (14.34%) subjects were homozygous for pathogenic mutations, 63 (5.91%) were compound heterozygotes, and 157 (14.71%) carried single heterozygous mutation. Furthermore, 65.28% (141/216) of these cases with two pathogenic mutations exhibited profound hearing loss. These data suggested that mutations in GJB2 gene are responsible for approximately 34.96% of non-syndromic hearing loss in Han Chinese population from Zhejiang Province in eastern China. In addition, our results also strongly supported the idea that other factors such as alterations in regulatory regions, additional genes, and environmental factors may contribute to the clinical manifestation of deafness.

Mitochondrial tRNA(Ser(UCN)) variants in 2651 Han Chinese subjects with hearing loss.

Mutations in the mitochondrial DNA have been associated with hearing loss. However, the prevalence and spectrum of mitochondrial tRNA mutations in hearing-impaired subjects are poorly understood. In this report, we have investigated the prevalence and spectrum of mitochondrial tRNA(Ser(UCN)) mutations in a large cohort of 2651 Han Chinese subjects with hearing loss. The clinical evaluation showed that 744 subjects (432 males and 312 females) had a history of exposure to aminoglycosides and other probands exhibited nonsyndromic hearing loss. Mutational analysis of tRNA(Ser(UCN)) gene identified 9 (8 known and 1 novel) variants. The prevalence of the known deafness-associated 7511T>C, 7505T>C and 7445A>C mutations was 0.04%, 0.04% and 0.04%, respectively. Other variants were evaluated by the evolutionary conservation, allelic frequency of Chinese controls, potential structural and functional alterations and pedigree analysis. Three variants were polymorphisms, while the 7444G>A, 7471DelG and 7496A>G variants were putative deafness-associated mutations. These putative deafness-associated variants accounted for 0.68% cases of hearing-impaired subjects in this cohort. The low penetrance of hearing loss in pedigrees carrying one of these putative deafness-associated mutations indicated that the mutation(s) is necessary but itself insufficient to produce a clinical phenotype. Other genetic or environmental factor(s) may influence the phenotypic manifestation of these tRNA(Ser(UCN)) mutations. Moreover, mtDNAs in 20 probands carrying one of the putative deafness-associated mutations were widely dispersed among 8 Eastern Asian haplogroups. In particular, the occurrences of haplogroups D4a, M22, and H2 in patients carrying the deafness-associated variants were higher than those in Chinese controls. These data further support that the mitochondrial tRNA(Ser(UCN)) gene is the hot spot for mutations associated with hearing loss. Thus, our findings may provide valuable information for the further understanding of pathophysiology and management of hearing loss.

[Expressions of matrix metalloproteinase-9 and interleukin-8 in nasopharyngeal carcinoma and association with Epstein-Barr virus latent membrane protein-1].

OBJECTIVE: To investigate the expressions of matrix metalloproteinase-9 (MMP-9) and interleukin-8 (IL-8) in nasopharyngeal carcinoma and their association with Epstein-Barr virus latent membrane protein-1 (LMP-1). METHOD: The expressions of MMP-9, IL-8 and LMP-1 were immunohistochemical studied in 53 nasopharyngeal carcinoma sections. We statistically analyzed the correlation of these data and also the relationship between the clinical features and the experimental data of these patients. RESULT: The positive expression rate of MMP-9, IL-8 and LMP-1 were all 66.04% (35/53) and their average expression score were (33.19 +/- 29.73)%, (33.46 +/- 30.23)%, (35.49 +/- 29.63)% respectively. The expressions of MMP-9 and IL-8 both showed positive correlation with the expression of LMP-1 (r = 0.792, 0.786 respectively). The expressions of MMP-9, IL-8 and LMP-1 showed significant relationship with lymph nodes metastasis (P < 0.05), but no-significant association with age, gender, pathological classification, and clinical stage. CONCLUSION: The expressions of MMP-9, IL-8 and LMP-1 were significantly associated with neck lymph nodes metastasis in nasopharyngeal carcinoma. The correlation between LMP-1 and MMP-9, IL-8 showed LMP-1 might enhance neck lymph nodes metastasis by up-regulating the expressions of MMP-9 and IL-8.