SNP Shot: Genomic Insights

Multiple pterygium syndrome is a congenital condition, meaning it's present at birth. It's characterized by skin webbing (pterygium) at the joints and reduced or absent fetal movement (akinesia). The akinesia often leads to muscle weakness and joint contractures (arthrogryposis), which limit joint mobility. Consequently, individuals with multiple pterygium syndrome may experience restricted movement, such as an inability to fully extend their arms and legs.

Multiple pterygium syndrome is classified into two forms based on symptom severity: Escobar type and lethal type. Escobar type (sometimes called Escobar syndrome) is the milder form, while lethal multiple pterygium syndrome is usually fatal before or shortly after birth.

In individuals with Escobar type multiple pterygium syndrome, skin webbing commonly affects the neck, fingers, forearms, inner thighs, and the backs of the knees. Arthrogryposis may also be present. Scoliosis (sideways curvature of the spine) can sometimes occur. Some individuals may experience respiratory distress at birth due to underdeveloped lungs (lung hypoplasia). Facial features often include droopy eyelids (ptosis), downward-sloping eyes (downslanting palpebral fissures), epicanthal folds (skin folds at the inner corners of the eyes), a small jaw, and low-set ears. Males may have undescended testes (cryptorchidism). Importantly, the condition doesn't worsen after birth, and muscle weakness isn't typically a long-term issue.

Lethal multiple pterygium syndrome shares many symptoms with the Escobar type. However, affected fetuses may also develop hydrops fetalis (excess fluid buildup in the body) or a cystic hygroma (a fluid-filled sac, usually on the neck). Severe arthrogryposis is a hallmark of this form. Lethal multiple pterygium syndrome is often associated with organ abnormalities, including hypoplasia (underdevelopment) of the heart, lungs, or brain; intestinal malrotation (twisting of the intestines); kidney abnormalities; cleft palate (opening in the roof of the mouth); and microcephaly (unusually small head size). A congenital diaphragmatic hernia, a hole in the diaphragm (muscle separating the abdomen and chest), may also occur. This form is usually fatal during the second or third trimester of pregnancy.

Inheritance:

Multiple pterygium syndrome is inherited in an autosomal recessive manner. This means that an affected individual must inherit two copies of the mutated gene, one from each parent. The parents, who each carry one copy of the mutated gene, typically don't exhibit any signs or symptoms of the condition.