Popliteal pterygium syndrome

Popliteal pterygium syndrome (PPS) (also called facio–genito–popliteal syndrome) is a rare genetic syndrome affecting the development of the face and orofacial region, skin, and genitalia. The features of the syndrome are highly variable. After birth, a cleft palate or cleft lip is often detected. A typical finding is a midline chin pit, which results from the presence of a salivary gland within the pit. A small nodular structure derived from subcutaneous tissue may also be present on the lower lip. In some individuals, missing teeth are observed.

Children with popliteal pterygium syndrome have web-like skin tissue in the popliteal fossa (behind the knee), which can restrict movement if not surgically corrected. There may also be fused or webbed fingers due to these tissue bands. Problems also include abnormally developed external genitalia, which are often hypoplastic (underdeveloped); boys may have undescended testes and a bifid scrotum.

Due to cleft lip and palate, there is delayed speech development, learning difficulties, and mild cognitive impairment. Intelligence itself is generally not different from the general population.

The incidence of popliteal pterygium syndrome is approximately 1:300,000. The syndrome is caused by a mutation in the IRF6 gene, which encodes a protein that plays an important role in early development, particularly in the formation of the face, skin, and genitalia.

The mutation is inherited in an autosomal dominant pattern. Only one copy of the mutated gene is sufficient for the syndrome to manifest.

Diagnosis:
Diagnosis is based on genetic testing in combination with clinical suspicion and the presence of characteristic symptoms.

Treatment:
Treatment is complex and includes surgical correction of the popliteal webbing to restore knee mobility. Multiple staged surgeries are required for cleft lip and/or palate, along with coordinated care from specialists (speech therapists, surgeons, ENT specialists, dentists, plastic surgeons, etc.), and early intervention programs when needed. Early surgical treatment of undescended testes is necessary to reduce the risk of infertility in males.

• Cleft palate and cleft lip
• Genital anomalies – hypoplasia of external genitalia (labia minora and labia majora), undescended testes, bifid scrotum
• Characteristic skin bands in the popliteal fossa (behind the knee), which restrict knee movement
• Typical facial features – a central chin pit and a nodular (“lump-like”) subcutaneous tissue formation on the lower lip
• Syndactyly (fused fingers), with band-like skin structures on the fingers causing them to be connected