A4 year baby is having large face, large jaw, large ear and macro orchidism is -: (A) Mc Cuneal bright syndrome, (B) Down's syndrome, (C) Cri-du chat syndrome, (D) Fragile X syndrome
Answer is D. Ans. is 'd' i.e., Fragile X syndrome Fragile X syndrome o Fragile X syndrome is the prototype of diseases in which the mutation is characterized by a long repeating sequence of three nucleotides. o Normally, a codon is triplet (trinucleotide). o In these type of disorders, this trinucleotide sequence undergoes amplification and the same sequence is repeated many times in the genome. o In most cases the affected equences share the nucleotide G and C. o Clinical features of fragile - X syndrome Mental retardation Hyperexntesible joint Long face with large mandible Large testis (macro-orchidism) High arched palate Mitral valve prolapse Large eveed ears