A 6-month-old boy presents with developmental delay and inability to sit unsupported. Vital signs show HR 110 bpm, RR 28, temp 37°C, SpO2 98%. On exam, he has marked hypotonia, tongue fasciculations, and absent deep tendon reflexes. CK level is elevated at 800 U/L. He denies respiratory distress. Family history is unremarkable. Which of the following genetic abnormalities is most likely present?

  1. A)Mutation in PMP22
  2. B)Trinucleotide repeat expansion in HTT
  3. C)Deletion of dystrophin on X chromosome
  4. D)Mutation in GAA
  5. E)Deletion of SMN1 geneGABARITO

Explicação

Spinal muscular atrophy is caused by deletion or mutation of SMN1, leading to degeneration of anterior horn cells. Infants present with severe hypotonia, weakness, areflexia, and sometimes tongue fasciculations. Ver explicação completa e trilha adaptativa →

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