A 3 year old boy is brought by his mother for evaluation of delayed development and mental retardation. He was also diagnosed with mild autism. On physical examination, his face is long with large mandible and his ears are large and elevated. His genetic workup reveals multiple repeats of nucleotide sequence CGG in the boy’s DNA. What is the most likely diagnosis of this boy’s condition? A- Fragile X-syndrome B- Duchenne myodystrophy C- Down syndrome D- Huntington’s disease E- Ataxia-telangiectasia http://medical-usmle.com/repeated-usmle-question-51
