Achondroplasia and Down's syndrome.

Down's syndrome in association with various other chromosomal disorders such as Klinefelter's, Turner's, trisomy 15, and triple X (Penrose and Smith, 1966), are well known. Other combinations of Down's syndrome with various metabolic disorders (e.g. hypothyroidism and diabetes mellitus (Daniels and Simon, 1968)) have also been reported. An unusual patient was recently seen at Columbus Children's Hospital with trisomy 21 in association with achondroplasia. The latter diagnosis was suspected at age 17 months, but Down's syndrome was not considered until the patient was referred to us for evaluation ofmental retardation at age 5 years.