Dados do Trabalho

Título

BECKER MUSCULAR DYSTROPHY AND SIBLINGS WITH DIFFERENT PHENOTYPES: CASE SERIES

Apresentação dos casos

Case 1, 20-year-old male with Becker muscular dystrophy (BMD), presenting with myalgia and cramps in the lower limbs on exertion. Neurological examination showed a hypophonic and nasal voice, asymmetrical elevation of the soft palate, tenar hypotrophy of the hands, generalized hypotonia, scoliosis, winged scapula, hypotrophy of the gluteal and intercostal muscles, enlargement of the calves, more significant proximal weakness in the upper limbs than in the lower limbs. Electroneuromyography with polyphasic low amplitude potentials on mild exertion. Laboratory tests showed elevated creatine phosphokinase (CK) 3446,6 U/L, normal myoglobinuria and lactate dehydroselase (LDH). Muscle biopsy with dystrophic alterations and reduced labeling of sarcoglycans and dystrophins. Case 2, 30 years old, male, with rheumatoid arthritis for 9 years, first consultation after assessing his brother (Case 1) with arthritis, myalgia on exertion, exercise intolerance (walking 5', climbing stairs), cramps. Neurological examination showed hypophonia, rectified smile, osteotendinous reflexes with hyporeflexia in the lower limbs and arreflexia in the upper limbs, hypertrophy in the calves and hypotrophy in the deltoids and glutes. Electroneuromyography showed a myopathic pattern. Laboratory tests showed normal CK 490 U/L, myoglobinuria and LDH. A neuromuscular genetic panel was carried out on the siblings and indicated that both had DMD gene dystrophinopathy, chrX position:31.910.296-31.972.231, CNV variation and consequent deletion of exons 45 to 47, copy 1 hemizygosity.

Discussão

Muscular dystrophies occur due to mutations in the DMD gene, which codes for dystrophin, in both Duchenne dystrophy (DMD) and BMD. There is progressive muscle degeneration with muscle weakness resulting from proximal predominance and pseudo calf hypertrophy. The dystrophinopathies are of X-linked inheritance, with late onset and mild presentation compared to DMD, but with greater cardiac involvement. DMB onset is around 12 years old, with loss of ambulation also varying from adolescence onwards.

Comentários finais

In this case series, we have two siblings with the same DMD mutation, but only one expresses the Becker Muscular Dystrophy (BMD) phenotype. We have been following up these patients for seven years and have been able to observe distinct progression of the dystrophinopathies. Patients follow up with cardiology for early identification of cardiomyopathies and physiotherapy.

Referências

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Waldrop MA, Flanigan KM. Update in Duchenne and Becker muscular dystrophy. Curr Opin Neurol. 2019 Oct;32(5):722-727. doi: 10.1097/WCO.0000000000000739. PMID: 31343429.
Flanigan KM. Duchenne and Becker muscular dystrophies. Neurol Clin. 2014 Aug;32(3):671-88, viii. doi: 10.1016/j.ncl.2014.05.002. PMID: 25037084.
Li M, Han Y, Wang S, Yu Y, Liu M, Xia Y, Weng Z, Zhou L, He X, Wang J, He Z, Yu L, Zha Y. Becker muscular dystrophy: case report, review of the literature, and analysis of differentially expressed hub genes. Neurol Sci. 2022 Jan;43(1):243-253. doi: 10.1007/s10072-021-05499-2. Epub 2021 Nov 3. PMID: 34731335.
Aartsma-Rus A, Ginjaar IB, Bushby K. The importance of genetic diagnosis for Duchenne muscular dystrophy. J Med Genet. 2016 Mar;53(3):145-51. doi: 10.1136/jmedgenet-2015-103387. Epub 2016 Jan 11. PMID: 26754139; PMCID: PMC4789806.

Palavras Chave

Becker muscular dystrophy; Genetics; Muscle disease