Autosomal dominant popliteal pterygium syndrome

Autosomal dominant popliteal pterygium syndrome (PPS), also known as facio-genito-popliteal syndrome, is a rare congenital disorder characterized by a combination of orofacial, musculoskeletal, and genitourinary anomalies. It is caused by mutations in the IRF6 gene, the same gene implicated in Van der Woude syndrome, and is inherited in an autosomal dominant pattern with variable expressivity. PPS is allelic to Van der Woude syndrome but generally presents with a broader and more severe spectrum of features. The hallmark feature of popliteal pterygium syndrome is the presence of webbing (pterygia) behind the knees (popliteal fossae), which can restrict leg movement and range from mild skin folds to extensive webs containing muscles, nerves, and blood vessels. Other key clinical features include cleft lip and/or cleft palate, lip pits (small depressions on the lower lip), syndactyly (webbing of fingers or toes), and genital anomalies such as cryptorchidism or scrotal malformations in males and labial hypoplasia in females. Additional findings may include ankyloblepharon filiforme adnatum (thin bands of tissue connecting the upper and lower eyelids), oral synechiae (bands connecting the upper and lower jaws), hypoplastic nails, and a distinctive pyramidal fold of skin over the hallux toenail. Treatment of popliteal pterygium syndrome is symptomatic and multidisciplinary. Surgical intervention is typically required to release popliteal webbing and improve mobility, repair cleft lip and palate, and address genital anomalies. Careful surgical planning is essential because the popliteal pterygia may contain the sciatic nerve or popliteal vessels. Orthopedic, plastic surgical, and urological specialists are often involved in the management of affected individuals. Genetic counseling is recommended for affected families given the autosomal dominant inheritance pattern and the 50% recurrence risk for offspring of affected individuals.

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