Popliteal Pterygium Syndrome - Genetics

Genetics

The genetic locus for PPS was localized to chromosome 1 in 1999. The disorder is inherited in an autosomal dominant manner and is due to mutation of the IRF6 gene. Most reported cases are sporadic; advanced parental age is found in a number of these cases, suggesting new mutations.

The term PPS has also been used for two rare autosomal recessively inherited conditions: Lethal PPS and PPS with Ectodermal Dysplasia. Although both conditions feature a cleft lip/palate, syngnathia, and popliteal pterygium, they are clinically distinguishable from the autosomal dominant case. Lethal PPS is differentiated by microcephaly, corneal aplasia, ectropion, bony fusions, hypoplastic nose and absent thumbs, while PPS with Ectodermal Dysplasia is differentiated by woolly hair, brittle nails, ectodermal anomalies, and fissure of the sacral vertebrae.