We report the case of a boy with achondroplasia and i(21q) Down syndrome. 
Besides craniofacial features typical in Down syndrome, the skeletal findings of 
achondroplasia dominate the clinical picture. The diagnosis of Down syndrome was 
based on clinical features and the cytogenetic finding of i(21q) trisomy 21. The 
diagnosis of achondroplasia was based on the presence of clinical and 
radiographic findings and confirmed by the presence of a common FGFR3 gene 
mutation (Gly380Arg) detected by restriction enzyme analysis and sequencing of 
the polymerase chain reaction products. This is the first report of 
achondroplasia associated with i(21q) Down syndrome.