DFNB59 Gene Mutations and its Association with Deafness in Schoolchildren in Kohgilooyeh & Boyerahmad Province

Introduction & Objective: Hearing loss is a common disease affecting millions of people worldwide. Hearing loss can be caused due to genetic or environmental factors or even both. The genetic of hearing defect is highly heterogeneous and more than 100 genes are predicted to cause this disorder in humans. A newly identified gene (DFNB59) has been shown to cause deafness in some populations. Here we report mutation analysis for DFNB59 gene in 88 genetic non-syndromic hearing loss subjects. Materials & Methods: In this descriptive-lab based study which was conducted at the Cellular and Molecular Research Center of Shahrekord University of Medical Sciences, DNA was extracted from the peripheral blood samples using standard phenol chloroform procedure. Mutation analysis for DFNB59 gene was performed using PCR-SSCP/HA protocol. The suspected DFNB59 which was detected as shifted bands on PAGE were then confirmed by direct sequencing strategy. Results: Two DFNB59 polymorphisms including c.793C>G and c.793C>T were detected in 8 and 1 deaf subjects respectively. Conclusion: We conclude that there is no association between DFNB59 mutations and deafness in the studied patients in the region

Study of three common mitochondrial mutations in Arab patients with nonsyndromic hearing loss in Khuzestan province, I.R.Iran

زمینه و هدف : ناشنوایی یکی از شایع ترین اختلالات حسی –عصبی است که در هر 1000 تولد زنده رخ می دهد. بیشتر ناشنوایی ها منشا ژنتیکی داشته و حدود 2-0 موارد ناشنوایی مربوط به جهش در ژن های میتوکندریایی است. این مطالعه با هدف بررسی فراوانی سه جهش میتوکندریایی A1555G ، A3243G و A7445G در ناشنوایان غیر سندرمیک استان خوزستان انجام شده است. روش بررسی: در این مطالعه توصیفی 62 دانش آموز ناشنوای غیر سندرومیک با الگوی اتوزومی مغلوب عرب استان خوزستان به روش آسان انتخاب شدند. DNA با روش استاندارد فنل کلروفرم استخراج و جهش های احتمالی در سه ژن میتوکندریایی شامل A1555G ، G3243A و A7445G با روش چند شکلی طول قطعه محدود ( PCR-RFLP ) غربالگری شد. در نهایت جهش های احتمالی به روش توالی یابی مستقیم مورد بررسی و تائید قرار گرفتند. یافته ها: در این مطالعه هیچ یک از جهش های A1555G ، A3243G و A7445G یافت نشد، با این حال دو جهش G3316A و A7445C در دو بیمار مورد مطالعه یافت شد. نتیجه گیری: این مطالعه نشان می دهد که جهش های میتوکندریایی G3316A و A7445C مسئول تعداد کمی از ناشنوایی های قبل از زبان باز کردن در جمعیت استان خوزستان می باشند و جهش های A1555G ، A3243G و A7445G در ایجاد ناشنوایی در این جمعیت نقشی نداشته اند. مطالعه ی حاضر خواهد توانست مشاوران ژنتیک در استان خوزستان را در برنامه مشاوره ژنتیک ناشنوایی خانواده ی بیماران ناشنوا یاری کند

Screening of three common mtDNA mutations among subjects with autosomal recessive non-syndromic hearing loss in Sistan va Baluchestan province, Iran

Background: Non-syndromic hearing loss may be induced by mutations in both nuclear and mitochondrial genes. Mutations in mtDNA are present in less than 1% of the children with pre-lingual deafness but are more prevalent later. Most of the molecular defects responsible for mitochondrial disorder, associated with hearing loss may be induced by mutations in the 12SrRNA and tRNA genes. This aim of this study was to investigate the frequency of three common mtDNA mutations including A1555G, A3243G and A7445G in a cohort of autosomal recessive non-syndromic hearing loss (ARNSHL) subjects in Sistan va Baluchestan province. Material and Methods: In this descriptive- experimental based study, a total of 110. ARNSHL subjects from Sistan va Baluchestan province were investigated for three common mtDNA mutations using PCR-RFLP procedure. The possible mutations were confirmed by direct sequencing. Results: None of the A1555G and A7445G mutations were detected in this study. However, we found one sample to carry A3243G mutation (0.9%). Moreover abolishing a MTTL1 restriction site close to A3243G mutation revealed a G3316A allelic variant in 0.9% of patients studied. Conclusion: This study showed that mtDNA mutations are responsible for less than 1% of pre-lingual ARNSHL associated subjects. The present study will improve the genetic counseling of hearing impaired patients in Sistan va Baluchestan province, Iran