Long QT syndrome associated with syndactyly identified in females.

The identification of female children with this syndrome is evidence that this disorder is not X-linked in inheritance. Possible inheritance modes still include autosomal recessive or, more likely, a de novo mutation, given the absence of family history in any of the patients. Children of both sexes with syndactyly should be screened with an electrocardiogram for this syndrome. Female children with this syndrome may have an increased risk of sudden death similar to male children.