Intrafamilial variability of popliteal pterygium syndrome: a family description.

Popliteal pterygium syndrome is one of the autosomal dominant limb pterygium syndromes. It has incomplete penetrance and extreme phenotypic variability that leads to difficulty in diagnosis. A case is presented to emphasize the variable phenotype of this disorder. The absence of pterygia in the family members led to the misdiagnosis of van der Woude's syndrome. However, the presence of a pyramidal fold of skin over the nail of the hallux in family members suggested the diagnosis of popliteal pterygium syndrome. It is concluded that the presence of this distinctive nail abnormality in infants with cleft lip, cleft palate or both suggests the diagnosis of the popliteal pterygium syndrome.