A 15-year-old boy presents with progressive gait instability and recurrent falls over 2 years. Vital signs: BP 118/76, HR 92, RR 16, temp 37°C. Examination reveals pes cavus deformity, absent ankle reflexes, extensor plantar responses, decreased vibration sense distally, and wide-based gait. Proprioception remains intact. Echocardiography shows hypertrophic cardiomyopathy. Serum vitamin B12 and folate levels are normal. Which genetic mutation best explains this constellation of findings?
- A)Loss of dystrophin in skeletal muscle
- B)Autosomal recessive GAA repeat expansion causing mitochondrial dysfunctionGABARITO
- C)Autosomal dominant degeneration of Purkinje cells
- D)Mutation in ATP7B causing copper accumulation
- E)Postinfectious autoimmune demyelination of peripheral nerves
Explicação
Autosomal recessive GAA repeat expansion causing mitochondrial dysfunction is correct. Friedreich ataxia is caused by a GAA trinucleotide repeat expansion in the frataxin gene, leading to degeneration of spinocerebellar tracts, dorsal columns, and corticospina... Ver explicação completa e trilha adaptativa →