Fassad Mahmoud R, Desouky Lubna M, Asal Samir, Abdalla Ebtesam M
Department of Human Genetics, Medical Research Institute, Alexandria University Egypt.
Department of Audiology, Alexandria Faculty of Medicine Egypt.
Int J Mol Epidemiol Genet. 2014 Dec 15;5(4):200-4. eCollection 2014.
BACKGROUND & AIM: Hearing loss is the most frequent form of neurosensory deficit in humans. Although the majority of hereditary hearing loss is due to nuclear gene mutations, it has become clear the significant contribution of mitochondrial genes. The first mitochondrial mutation shown to cause non-syndromic hearing loss in humans was the A1555G mutation in the small ribosomal RNA gene (12S rRNA). It has been detected in hundreds of families of different ethnic backgrounds, making it one of the prevalent genetic causes of hearing loss currently identified. However, there are major differences between ethnic groups regarding the frequency of this mutation. Few studies have been made in Arab countries, especially in Egypt. Here we report the prevalence of the mitochondrial mutation A1555G among patients with non-syndromic hearing loss (NSHL) and in healthy individuals with normal hearing in the Egyptian population.
SUBJECTS & METHODS: The study was conducted on 97 patients with SNHL and 300 unrelated healthy Egyptian individuals, with normal hearing, as normal control subjects. Polymerase chain reaction followed by restriction enzyme digestion was used to screen the DNA samples of all subjects for the A1555G mutation.
Participants included 97 cases with SNHL, 46 males and 51 females. Their ages ranged from 1 month to 65 years with the mean age 6.2 years (SD ± 8.2). Paternal consanguinity was reported in 46% (35/76) of the studied families. The A1555G mutation was found in one of the 97 patients (1.3%), while it has not been detected in the 300 control samples.
Our findings indicate that, even in absence of exposure to aminoglycosides, the mitochondrial A1555G mutation is one of the potential causes of non-syndromic SNHL in the Egyptian population.
听力损失是人类最常见的神经感觉缺陷形式。尽管大多数遗传性听力损失是由核基因突变引起的，但线粒体基因的重要作用已变得清晰。首个被证明可导致人类非综合征性听力损失的线粒体突变是小核糖体RNA基因（12S rRNA）中的A1555G突变。该突变已在数百个不同种族背景的家族中被检测到，使其成为目前已确定的听力损失的常见遗传原因之一。然而，不同种族群体在该突变频率上存在重大差异。在阿拉伯国家，尤其是埃及，相关研究较少。在此，我们报告埃及人群中非综合征性听力损失（NSHL）患者及听力正常的健康个体中线粒体A1555G突变的患病率。
本研究对97例重度感音神经性听力损失（SNHL）患者和300名听力正常的埃及无关健康个体进行，后者作为正常对照。采用聚合酶链反应（PCR）后进行限制性酶切消化，对所有受试者的DNA样本进行A1555G突变筛查。
参与者包括97例SNHL患者，其中男性46例，女性51例。年龄范围为1个月至65岁，平均年龄6.2岁（标准差±8.2）。在所研究的家庭中，46%（35/76）报告有父系近亲结婚情况。97例患者中有1例（1.3%）检测到A1555G突变，而300份对照样本中未检测到该突变。
我们的研究结果表明，即使在未接触氨基糖苷类药物的情况下，线粒体A1555G突变也是埃及人群中非综合征性SNHL的潜在病因之一。
