Molecular studies have confirmed that it is a heterogeneous disorder and there may be evidence for an autosomal recessive mode of inheritance.1 The gene responsible for Noonan' syndrome has been mapped to the long arm of chromosome 12.2,3 The human deltex gene (DLT x 1), mapping to chromosomal region 12q24 in the vicinity of the Noonan's syndrome critical region is being evaluated as a candidate gene for this disorder.4 Various types of musculoskeletal abnormalities have been reported, including short stature, craniofacial dysmorphism, short or webbed neck and fetal pads in fingers and toes.5 We report five cases with the unusual physical features of overriding toes and simian creases.
Among the novel mutations in EXT1, c.1004T>G-associated HME exhibited overriding toes and scoliosis, c.1883+2T>A-associated HME exhibited brachydactyly, and c.459_460delCT-associated exostosis arising from vertebra T4 caused spinal cord compression.