Popliteal pterygium syndrome

Alternate names

PPS; Cleft lip/palate paramedian mucous cysts of the lower lip popliteal pterygium digital and genital anomalies; Faciogenitopopliteal syndrome

Definition

Popliteal pterygium syndrome is a condition that affects the development of the face, skin, and genitals.

Epidemiology

Popliteal pterygium syndrome is a rare condition, occurring in approximately 1 in 300,000 individuals.

Cause

• Mutations in the IRF6 gene cause popliteal pterygium syndrome.
• The IRF6 gene provides instructions for making a protein that plays an important role in early development.
• This protein is a transcription factor, which means that it attaches (binds) to specific regions of DNA and helps control the activity of particular genes.
• The IRF6 protein is active in cells that give rise to tissues in the head and face.
• It is also involved in the development of other parts of the body, including the skin and genitals.

Gene mutations

• Mutations in the IRF6 gene that cause popliteal pterygium syndrome may change the transcription factor's effect on the activity of certain genes.
• This affects the development and maturation of tissues in the face, skin, and genitals, resulting in the signs and symptoms of popliteal pterygium syndrome.

Inheritance

Autosomal dominant pattern, a 50/50 chance.

This condition is inherited in an autosomal dominant pattern, which means one copy of the altered gene in each cell is sufficient to cause the disorder.

Signs and symptoms

• Most people with this disorder are born with a cleft lip, a cleft palate (an opening in the roof of the mouth), or both. Affected individuals may have depressions (pits) near the center of the lower lip, which may appear moist due to the presence of salivary and mucous glands in the pits.
• Small mounds of tissue on the lower lip may also occur.
• In some cases, people with popliteal pterygium syndrome have missing teeth.
• Individuals with popliteal pterygium syndrome may be born with webs of skin on the backs of the legs across the knee joint, which may impair mobility unless surgically removed.
• Affected individuals may also have webbing or fusion of the fingers or toes (syndactyly), characteristic triangular folds of skin over the nails of the large toes, or tissue connecting the upper and lower eyelids or the upper and lower jaws.
• They may have abnormal genitals, including unusually small external genital folds (hypoplasia of the labia majora) in females.
• Affected males may have undescended testes (cryptorchidism) or a scrotum divided into two lobes (bifid scrotum).
• People with popliteal pterygium syndrome who have cleft lip and/or palate, like other individuals with these facial conditions, may have an increased risk of delayed language development, learning disabilities, or other mild cognitive problems.
• The average IQ of individuals with popliteal pterygium syndrome is not significantly different from that of the general population.

For most diseases, symptoms will vary from person to person. People with the same disease may not have all the symptoms listed. 80%-99% of people have these symptoms

• Cleft palate(Cleft roof of mouth)
• Generalized hirsutism(Excessive hairiness over body)
• Joint stiffness(Stiff joint)
• Micrognathia(Little lower jaw)
• Thin upper lip vermilion(Thin upper lip)
• Toe syndactyly(Fused toes)

30%-79% of people have these symptoms

• Abnormality of the nail
• Abnormality of the ribs(Rib abnormalities)
• Ankyloblepharon(Adhesion of eyelids)
• Bifid scrotum(Cleft of scrotum)
• Cryptorchidism(Undescended testes)
• Fibrous syngnathia
• Finger syndactyly
• Hypoplastic labia majora(Small labia majora)
• Lip pit
• Nonketotic hyperglycinemia
• Non-midline cleft lip
• Popliteal pterygium
• Scoliosis
• Scrotal hypoplasia(Smaller than typical growth of scrotum)

5%-29% of people have these symptoms

• Ambiguous genitalia(Ambiguous external genitalia)
• Choanal atresia(Blockage of the rear opening of the nasal cavity)
• Specific learning disability
• Split hand(Claw hand)

Diagnosis

To make the diagnosis of popliteal pterygium syndrome, an individual must have (1) the lip and/or palate anomalies listed for Van der Woude syndrome and one or more of the following:[1]

• Popliteal pterygia
• Syndactyly
• Abnormal external genitalia
• Ankyloblepharon
• Pyramidal skin on the hallux
• A spectrum of intraoral adhesions, the most severe of which is complete syngnathia

The diagnosis of an IRF6-related disorder is confirmed by detection of a heterozygous pathogenic variant in IRF6.

Treatment

Treatment may include reconstructive surgery for the oral defects, such as the cleft lip and cleft palate, and for other defects such as the popliteal pterygium or abnormal genitalia.[2].

Management is supportive/symptomatic.

• Cleft lip. Management is surgical, dental, and orthodontic.
• Cleft palate. In addition to surgery, dentistry, and orthodontics, speech therapy and audiologic evaluation are usually needed.
• Otolaryngology evaluation is needed for management of middle ear effusions.
• Lip pits. Surgery may be indicated for cosmetic purposes or for lip function. The lip pits may be connected to mucous-secreting glands and may be excised for this.
• Eyelid and oral synechiae (ankyloblepharon and syngnathia, respectively) may require surgical excision.
• Syngnathia often requires emergent release due to feeding and respiratory concerns and may require tracheotomy.
• Popliteal pterygium. Management involves physical therapy and surgical and orthopedic intervention, as necessary.
• Syndactyly may require surgery.
• Abnormal genitalia may require surgery especially in the presence of cryptorchidism. The genital anomalies may result in infertility.

NIH genetic and rare disease info

• NIH info on Popliteal pterygium syndrome

Popliteal pterygium syndrome is a rare disease.

Popliteal pterygium syndrome Resources
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