Bakhchane Amina, Charif Majida, Salime Sara, Boulouiz Redouane, Nahili Halima, Roky Rachida, Lenaers Guy, Barakat Abdelhamid
Laboratoire de Génétique Moléculaire Humaine, Département de Recherche Scientifique, Institut Pasteur du Maroc, Casablanca, Morocco.
Laboratoire de Génétique Moléculaire Humaine, Département de Recherche Scientifique, Institut Pasteur du Maroc, Casablanca, Morocco; Institut des Neurosciences de Montpellier, U1051 de l'INSERM, Université de Montpellier, BP 74103, 34091 Montpellier cedex 05, France; PREMMi, Mitochondrial Medicine Research Centre, Université d'Angers, CHU Bât IRIS/IBS, Rue des Capucins, 49933 Angers cedex 9, France.
PLoS One. 2015 Sep 15;10(9):e0138072. doi: 10.1371/journal.pone.0138072. eCollection 2015.
Mutations in the TBC1D24 gene are responsible for four neurological presentations: infantile epileptic encephalopathy, infantile myoclonic epilepsy, DOORS (deafness, onychodystrophy, osteodystrophy, mental retardation and seizures) and NSHL (non-syndromic hearing loss). For the latter, two recessive (DFNB86) and one dominant (DFNA65) mutations have so far been identified in consanguineous Pakistani and European/Chinese families, respectively. Here we report the results of a genetic study performed on a large Moroccan cohort of deaf patients that identified three families with compound heterozygote mutations in TBC1D24. Four novel mutations were identified, among which, one c.641G>A (p.Arg214His) was present in the three families, and has a frequency of 2% in control Moroccan population with normal hearing, suggesting that it acts as an hypomorphic variant leading to restricted deafness when combined with another recessive severe mutation. Altogether, our results show that mutations in TBC1D24 gene are a frequent cause (>2%) of NSHL in Morocco, and that due to its possible compound heterozygote recessive transmission, this gene should be further considered and screened in other deaf cohorts.
TBC1D24基因的突变导致四种神经系统表现:婴儿癫痫性脑病、婴儿肌阵挛性癫痫、DOORS(耳聋、甲营养不良、骨营养不良、智力迟钝和癫痫发作)和非综合征性听力损失(NSHL)。对于后者,目前分别在近亲通婚的巴基斯坦家庭和欧洲/中国家庭中鉴定出两种隐性(DFNB86)和一种显性(DFNA65)突变。在此,我们报告了一项针对大量摩洛哥耳聋患者队列进行的基因研究结果,该研究鉴定出三个在TBC1D24基因中存在复合杂合子突变的家庭。鉴定出四个新突变,其中一个c.641G>A(p.Arg214His)存在于这三个家庭中,在听力正常的摩洛哥对照人群中的频率为2%,这表明当与另一个隐性严重突变结合时,它作为一种亚效变体导致局限性耳聋。总之,我们的结果表明,TBC1D24基因突变是摩洛哥NSHL的常见病因(>2%),并且由于其可能的复合杂合子隐性遗传,该基因应在其他耳聋队列中进一步考虑并进行筛查。