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Becker muscular dystrophy presenting with mental retardation induced by exons deletion of Dystrophin gene

作者:Kong Weijing 等 日期:2021-07-16 浏览量:276

第八届北京罕见病学术大会暨2020京津冀罕见病学术大会征文(128)

1. Department of Pediatrics, Beijing Friendship Hospital, Capital Medical University,

2. Department of Pediatrics, Chinese PLA General Hospital,

*Correspondence: Meng Yan, mystong@126.com

Kong Weijing1,2, Meng Yan2*

Background: Becker muscular dystrophy (BMD) is X-linked recessive hereditary disorder due to mutations in the DMD gene, which consists of 79 exons encoding the dystrophin protein. Mental retardation, an infrequent manifestation of BMD, and evaluated serum creatine kinase (CK) which are the only two symptoms related with this disorder are extremely rare.

Method: Case history, clinical examination, and genetic testing were performed in family members.

Result: A 14-year-old boy presented to our hospital with mental retardation. He was G2P1, a full-term baby, with a birth weight of 3.4 kg. Development milestones were generally normal, but language development was delayed. He started speaking “dad” and “mom” about 3-year-old. When he presented to us, his weight was 53 kg (>P50), height was 165 cm (>P50) and head circumference was 57.5 cm. The patient had normal hearing and vision without special face. There is no obvious change of his calves. He showed no decreased activity. Febrile convulsion attacked him once when he was about 2 years old, but never showed again. Serum creatine kinase level was markedly elevated (1896.6 U/L). This value is higher in stress (7702U/L). Low intelligence quotient (IQ = 56) was revealed by Wechsler intelligence tests. Multiplex ligation-dependent probe amplification showed deletion of exons 45–48 in the Dystrophin gene, which was inherited from his mother. His mother also showed mental retardation, but she had less serious symptom.

Conclusions: In this case, we reported a BMD patient with mental retardation and normal motor development, while his serum creatine phosphokinase level is elevated. BMD may only show mental retardation, with elevated serum creatine kinase level, without muscular hypertrophy and weakness. The present case report helps to better understand the clinical and genetic features of BMD.

Keywords: Becker muscular dystrophy, Genetic analysis, Metal retardation