Unusual dysmorphic features in five patients with Noonan's syndrome: a brief review

Abstract

Noonan's syndrome is a relatively common, multiple congenital anomaly syndrome, genetically inherited as an autosomal dominant disorder with variable penetrance. It is defined by a characteristic phenotype, congenital heart disease, ocular defects and mild mental retardation. 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. Such abnormalities can be considered among the minor manifestations of the syndrome.