A 4-year baby is having a large face, large jaw, large ear and macroorchidism is –
Fragile X syndrome

Fragile X syndrome is the prototype of diseases in which the mutation is characterized by a long repeating sequence of three nucleotides.
Normally, a codon is triplet (trinucleotide).
In these type of disorders, this trinucleotide sequence undergoes amplification and the same sequence is repeated many times in the genome.
In most cases, the affected sequences share the nucleotide G and C.


Clinical features of fragile - X syndrome

Mental retardation                                      
Large testis (macroorchidism)                        
Large everted ears
Hyperextensible joint 
Long face with large mandible
High arched palate  
Mitral valve prolapse
Mc Cuneal bright syndrome
Down's syndrome
Cri–du chat syndrome
Fragile X syndrome