Öztürk Özden, Çavdartepe Büşra Eser, Bağış Haydar
Department of Medical Genetics, Medical Faculty, Adiyaman University, Adiyaman, Turkey.
Department of Medical Genetics, Adiyaman University Training and Research Hospital, Adiyaman, Turkey.
Mol Syndromol. 2022 May;13(3):246-253. doi: 10.1159/000519640. Epub 2022 Feb 4.
Spinal muscular atrophy, X-linked 2 (SMAX2) is a rare type of spinal muscular atrophy characterized by muscle weakness, hypotonia, areflexia, myopathic face, tongue fibrillations, contractures, bone fractures, and cryptorchidism. Variants of the gene lead to SMAX2. The gene encodes a protein that activates the ubiquitin pathway which is responsible for protein degradation. Here, we describe a family presenting with hypotonia, muscle weakness, areflexia, contractures, weak cry, in association with other anomalies including myopathic face, scoliosis, tongue fibrillations, and cryptorchidism. Molecular analysis in 2 patients revealed a hemizygous pathogenic variant in the gene (NM_153280.3, NP_695012.1: c.1731C>T [p.Asn577Asn]) inherited from their carrier mothers. Our study presents the first patients from Turkey, widening the phenotypic spectrum of SMAX2 by pectus carinatum, medullary sponge kidney, and frontal cyst.
X连锁2型脊髓性肌萎缩症（SMAX2）是一种罕见的脊髓性肌萎缩症，其特征为肌肉无力、肌张力减退、无反射、肌病面容、舌肌纤维震颤、挛缩、骨折和隐睾。该基因的变异导致SMAX2。该基因编码一种激活泛素途径的蛋白质，泛素途径负责蛋白质降解。在此，我们描述了一个家系，其成员表现为肌张力减退、肌肉无力、无反射、挛缩、哭声微弱，并伴有其他异常，包括肌病面容、脊柱侧弯、舌肌纤维震颤和隐睾。对2名患者的分子分析显示，他们从携带致病基因的母亲那里遗传了该基因（NM_153280.3，NP_695012.1：c.1731C>T [p.Asn577Asn]）中的一个半合子致病变异。我们的研究报告了来自土耳其的首例患者，通过鸡胸、髓质海绵肾和额叶囊肿拓宽了SMAX2的表型谱。
