A 7-year-old boy presents with declining school performance and behavioral difficulties. Vital signs are normal (BP 110/68, HR 82, RR 20, Temp 37°C). Examination reveals a long narrow face, large everted ears, hyperextensible fingers, and macroorchidism. His maternal uncle had an identical phenotype. Serum creatinine and liver function tests are normal. IQ testing shows mild intellectual disability. He denies seizures. Expansion of which of the following nucleotide repeats is the most likely cause?
- A)CTG
- B)GAA
- C)ATTCT
- D)CGGGABARITO
- E)CAG
Explicação
Fragile X syndrome is caused by CGG trinucleotide repeat expansion in the FMR1 gene, leading to hypermethylation and reduced gene expression. The condition is X linked and classically causes intellectual disability, macroorchidism, large ears, and a long face.... Ver explicação completa e trilha adaptativa →