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Gap Junction Protein Beta 2 Gene Variants and Non-Syndromic Hearing Impairment among Couples Referred For Prenatal Diagnosis in the Northeast of Iran.

ABSTRACT: Introduction:Hearing impairment is a complex medical disorder which has genetic and non-genetic causes. Gap Junction Protein Beta 2 (GJB2) gene variant is a well-known disease-causing gene among patients with hearing impairment. The frequencies of genetic variants in the GJB2 gene are different in each population. This study aimed to discuss the GJB2 gene status in an Iranian population with hearing impairment who referred for prenatal testing. Materials and Methods:This cross-sectional study was conducted in a genetic laboratory affiliated with Mashhad Jahad Daneshgahi, Mashhad, Iran. A total number of 21 bilateral hearing impaired patients were enrolled in this study. The exons for target GJB2 gene were amplified by polymerase chain reaction after the confirmation of the hearing impairment and the exclusion of the acquired causes of hearing loss. Results:The c.35delG and c.79G>A variants were the first and second most common variants in the study population, respectively. The mean age of the patients was 27.5 (8.7) years and 12 cases were male. There was no significant association between hearing impairment degree and age and heterozygosity status (P=0.376 and P=.074 respectively). Conclusion:The c.35delG and c.79G>A variants were determined as the first and second most common variants in the GJB2 gene, respectively. The mean age of 26 years in this study population indicates the late referral for the evaluation of the hearing difficulty. Furthermore, it highlights the further need to encourage families with a history of hearing impairment to engage in genetic counseling.

SUBMITTER: Vojdani S

PROVIDER: S-EPMC6449530 | biostudies-literature | 2019 Mar

REPOSITORIES: biostudies-literature

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Gap Junction Protein Beta 2 Gene Variants and Non-Syndromic Hearing Impairment among Couples Referred For Prenatal Diagnosis in the Northeast of Iran.

Vojdani Samaneh S Jafarzadeh Esfehani Reza R Iranmanesh Vahid V Davari Hafezeh H Amini Nafiseh N Jaripour Mohammad Ehsan ME Zargari Peyman P Dastpak Mahtab M Sadrnabavi Ariane A

Iranian journal of otorhinolaryngology 20190301 103

<h4>Introduction</h4>Hearing impairment is a complex medical disorder which has genetic and non-genetic causes. Gap Junction Protein Beta 2 (GJB2) gene variant is a well-known disease-causing gene among patients with hearing impairment. The frequencies of genetic variants in the GJB2 gene are different in each population. This study aimed to discuss the GJB2 gene status in an Iranian population with hearing impairment who referred for prenatal testing.<h4>Materials and methods</h4>This cross-sec ...[more]

PMID: 30989077

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Project description:Our study aimed to investigate GJB2 (connexin 26) and GJB6 (connexin 30) mutations associated with non-syndromic childhood hearing impairment (HI) as well as the environmental causes of HI in Ghana. Medical reports of 1,104 students attending schools for the deaf were analyzed. Families segregating HI, as well as isolated cases of HI of putative genetic origin were recruited. DNA was extracted from peripheral blood followed by Sanger sequencing of the entire coding region of GJB2. Multiplex PCR and Sanger sequencing were used to analyze the prevalence of GJB6-D3S1830 deletion. Ninety-seven families segregating HI were identified, with 235 affected individuals; and a total of 166 isolated cases of putative genetic causes, were sampled from 11 schools for the deaf in Ghana. The environmental factors, particularly meningitis, remain a major cause of HI impairment in Ghana. The male/female ratio was 1.49. Only 59.6% of the patients had their first comprehensive HI test between 6 to 11 years of age. Nearly all the participants had sensorineural HI (99.5%; n = 639). The majority had pre-lingual HI (68.3%, n = 754), of which 92.8% were congenital. Pedigree analysis suggested autosomal recessive inheritance in 96.9% of the familial cases. GJB2-R143W mutation, previously reported as founder a mutation in Ghana accounted for 25.9% (21/81) in the homozygous state in familial cases, and in 7.9% (11/140) of non-familial non-syndromic congenital HI cases, of putative genetic origin. In a control population without HI, we found a prevalent of GJB2-R143W carriers of 1.4% (2/145), in the heterozygous state. No GJB6-D3S1830 deletion was identified in any of the HI patients. GJB2-R143W mutation accounted for over a quarter of familial non-syndromic HI in Ghana and should be investigated in clinical practice. The large connexin 30 gene deletion (GJB6-D3S1830 deletion) does not account for of congenital non-syndromic HI in Ghana. There is a need to employ next generation sequencing approaches and functional genomics studies to identify the other genes involved in most families and isolated cases of HI in Ghana.

Project description:Objective The objective of this study is to evaluate whether there is an association between in-utero exposure to nicotine and subsequent hearing dysfunction.Patients and methods Secondary analysis of a multicenter randomized trial to prevent congenital cytomegalovirus (CMV) infection among gravidas with primary CMV infection was conducted. Monthly intravenous immunoglobulin hyperimmune globulin therapy did not influence the rate of congenital CMV. Dyads with missing urine, fetal or neonatal demise, infants diagnosed with a major congenital anomaly, congenital CMV infection, or with evidence of middle ear dysfunction were excluded. The primary outcome was neonatal hearing impairment in one or more ears defined as abnormal distortion product otoacoustic emissions (DPOAEs; 1 to 8 kHz) that were measured within 42 days of birth. DPOAEs were interpreted using optimized frequency-specific level criteria. Cotinine was measured via enzyme-linked immunosorbent assay kits in maternal urine collected at enrollment and in the third trimester (mean gestational age 16.0 and 36.7 weeks, respectively). Blinded personnel ran samples in duplicates. Maternal urine cotinine >5 ng/mL at either time point was defined as in-utero exposure to nicotine. Multivariable logistic regression included variables associated with the primary outcome and with the exposure (p < 0.05) in univariate analysis.Results Of 399 enrolled patients in the original trial, 150 were included in this analysis, of whom 46 (31%) were exposed to nicotine. The primary outcome occurred in 18 (12%) newborns and was higher in nicotine-exposed infants compared with those nonexposed (15.2 vs. 10.6%, odds ratio [OR] 1.52, 95% confidence interval [CI] 0.55-4.20), but the difference was not significantly different (adjusted odds ratio [aOR] = 1.0, 95% CI 0.30-3.31). This association was similar when exposure was stratified as heavy (>100 ng/mL, aOR 0.72, 95% CI 0.15-3.51) or mild (5-100 ng/mL, aOR 1.28, 95% CI 0.33-4.95). There was no association between nicotine exposure and frequency-specific DPOAE amplitude.Conclusion In a cohort of parturients with primary CMV infection, nicotine exposure was not associated with offspring hearing dysfunction assessed with DPOAEs.Key points· Nicotine exposure was quantified from maternal urine.. · Nicotine exposure was identified in 30% of the cohort.. · Exposure was not associated with offspring hearing dysfunction..

Dataset Information

Gap Junction Protein Beta 2 Gene Variants and Non-Syndromic Hearing Impairment among Couples Referred For Prenatal Diagnosis in the Northeast of Iran.

Publications

Gap Junction Protein Beta 2 Gene Variants and Non-Syndromic Hearing Impairment among Couples Referred For Prenatal Diagnosis in the Northeast of Iran.

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