SNP Shot: Genomic Insights

Fraser syndrome is a rare genetic condition present from before birth that affects development. Key characteristics include cryptophthalmos (eyes covered by skin and often malformed), cutaneous syndactyly (skin fusion between fingers and toes), and genitourinary anomalies (abnormalities of the genitals and urinary tract). Other organs and tissues can also be affected. The severity of Fraser syndrome varies; in severe cases, it can be fatal around the time of birth, while less severely affected individuals may live into childhood or adulthood.

Cryptophthalmos is a hallmark of Fraser syndrome. Typically, both eyes are completely covered by skin, though sometimes only one eye is affected, or the coverage is partial. In cryptophthalmos, the eyes may also be malformed, such as being fused to the overlying skin or being abnormally small (microphthalmia) or absent (anophthalmia). These eye abnormalities often lead to impaired or lost vision. Other related eye issues may include missing eyebrows or eyelashes, or a patch of hair extending from the hairline to the eyebrow.

Cutaneous syndactyly in Fraser syndrome commonly affects both hands and feet. The skin between the middle three fingers and toes is most often fused, but other digits can also be involved. Additional hand and foot abnormalities are possible.

Genital abnormalities in individuals with Fraser syndrome can include an enlarged clitoris in females or undescended testes (cryptorchidism) in males. In some cases, the external genitalia are ambiguous, making it difficult to determine if they are clearly female or male.

Renal agenesis, the absence of one or both kidneys, is the most frequent urinary tract abnormality in Fraser syndrome. Other kidney problems, or abnormalities of the bladder and other urinary tract components, can also occur.

Fraser syndrome can manifest in a variety of other signs and symptoms, including heart defects or abnormalities of the larynx (voicebox) or other parts of the respiratory system. Some individuals also have facial abnormalities, such as ear or nose malformations, or cleft lip (with or without cleft palate).

Inheritance:

Fraser syndrome follows an autosomal recessive inheritance pattern. This means that both copies of the relevant gene in each cell must have mutations for the condition to develop. Individuals with Fraser syndrome inherit one mutated copy of the gene from each parent, who are carriers and typically do not exhibit signs or symptoms of the condition themselves.