Mahdieh Nejat, Bagherian Hamideh, Shirkavand Atefeh, Sharafi Maryam, Zeinali Sirous
Department of Medical Genetics, School of Medical Sciences, Tarbiat Modares University, Tehran, Iran.
Int J Pediatr Otorhinolaryngol. 2010 Sep;74(9):1089-91. doi: 10.1016/j.ijporl.2010.06.005. Epub 2010 Jul 6.
Hearing loss is the most common sensory defect in the world. The genetic basis of this condition is very complex. Molecular variations in GJB2 gene are the common cause of hearing impairment in Caucasians. One expects that affected members of a family with same mutation have similar phenotype. Here, we report phenotypic variability in hearing loss among the members of a Lur family. Two brothers from a Lur family from Lurestan province in western Iran with variable degrees of nonsyndromic sensorineural hearing loss were evaluated for genetic counseling. Clinical examinations, audiological tests and molecular studies including GJB2 gene sequencing and detection of Delta(GJB6-D13S1830) deletion were performed. Sequencing analysis of GJB2 gene revealed delE120 mutation in both brothers in homozygous form. Since one of them was profoundly deaf and the other was mild hearing loss and had normal conversation, we were expecting different genotypes or other causative effects. Delta(GJB6-D13S1830) was not found. Phenotypic variability between members of different families with the same type of mutation can be expected which may be due to the role of different modifying factors, unrecognized gap junction isoforms, or polymorphism effects.
听力损失是世界上最常见的感觉缺陷。这种情况的遗传基础非常复杂。GJB2基因的分子变异是高加索人听力障碍的常见原因。人们预期具有相同突变的家族中受影响的成员具有相似的表型。在此，我们报告了一个卢尔家族成员中听力损失的表型变异性。对来自伊朗西部卢里斯坦省一个卢尔家族的两名患有不同程度非综合征性感音神经性听力损失的兄弟进行了遗传咨询评估。进行了临床检查、听力测试以及包括GJB2基因测序和检测Delta(GJB6-D13S1830)缺失在内的分子研究。GJB2基因的测序分析显示，两兄弟均为纯合形式的delE120突变。由于其中一人严重失聪，另一人听力轻度损失且能正常交谈，我们预期会有不同的基因型或其他致病因素。未发现Delta(GJB6-D13S1830)。可以预期具有相同类型突变的不同家族成员之间存在表型变异性，这可能是由于不同修饰因子、未识别的间隙连接亚型或多态性效应的作用。
