SNP Shot: Genomic Insights

Ankyloblepharon-ectodermal defects-cleft lip/palate (AEC) syndrome is a type of ectodermal dysplasia. Ectodermal dysplasias are a group of approximately 180 conditions that cause abnormal development of tissues derived from the ectoderm, such as skin, hair, nails, teeth, eyes, ears, and sweat glands.

AEC syndrome often presents with areas of missing skin, called erosion. In babies with AEC syndrome, this erosion typically occurs on the scalp. This skin erosion tends to recur throughout life, affecting the scalp, neck, hands, and feet. The severity of skin erosion varies, ranging from mild to severe, and can result in life-threatening infections in infancy, as well as scarring and hair loss. Other ectodermal abnormalities associated with AEC syndrome include changes in skin pigmentation, brittle, sparse, or absent hair, deformed or missing fingernails and toenails, and malformed or missing teeth. Individuals with AEC syndrome may also experience difficulties regulating their body temperature due to missing or malfunctioning sweat glands, leading to overheating or hypothermia.

Many infants with AEC syndrome are born with ankyloblepharon filiforme adnatum, a condition where strands of tissue fuse the upper and lower eyelids together. Most individuals with AEC syndrome are also born with a cleft palate (an opening in the roof of the mouth), a cleft lip (a split in the lip), or both. These clefts can make it difficult for infants to suckle, often causing feeding problems and a failure to thrive (inadequate growth and weight gain).

Other features of AEC syndrome may include limb abnormalities, most commonly syndactyly (fused fingers or toes). Less frequently, individuals may exhibit camptodactyly (permanently bent fingers or toes) or ectrodactyly (a deep split in the hands or feet with missing fingers or toes and fusion of the remaining digits). Hearing loss is common, affecting over 90% of children with AEC syndrome. Some individuals also have distinctive facial features, such as small jaws that cannot open fully and a narrow philtrum (the space between the upper lip and nose). Additional signs and symptoms can include hypospadias (opening of the urethra on the underside of the penis) in males, digestive issues, absent tear duct openings, and chronic sinus or ear infections.

Rapp-Hodgkin syndrome shares many of the same signs and symptoms as AEC syndrome. Initially classified as separate disorders, it was later discovered that both result from mutations in the same part of the same gene. Consequently, most researchers now consider Rapp-Hodgkin syndrome and AEC syndrome to be manifestations of a single disease spectrum.

Inheritance:

AEC syndrome is inherited in an autosomal dominant manner. This means that only one copy of the mutated gene is needed in each cell to cause the disorder.