SNP Shot: Genomic Insights

Keratitis-ichthyosis-deafness (KID) syndrome is a disorder characterized by a triad of symptoms: eye problems, skin abnormalities, and hearing impairment.

Individuals with KID syndrome typically develop keratitis, an inflammation of the cornea, the eye's outer surface. This inflammation can cause pain, heightened sensitivity to light (photophobia), the formation of new blood vessels on the cornea (neovascularization), and corneal scarring. Over time, these complications can lead to reduced vision (decreased visual acuity), and in severe instances, blindness.

A common skin manifestation of KID syndrome is palmoplantar keratoderma, characterized by thick, hardened skin on the palms and soles. Additionally, affected individuals often exhibit erythrokeratoderma, featuring thick, red, dry, and scaly patches of skin (ichthyosis). While these patches can appear anywhere, they are most frequently observed on the neck, groin, and armpits. Skin breaks are common and can become infected, posing a life-threatening risk, particularly in infants. Approximately 12% of individuals with KID syndrome are prone to developing squamous cell carcinoma, a type of skin cancer that can also affect mucous membranes like those lining the mouth.

Partial hair loss is frequently observed in KID syndrome, often impacting the eyebrows and eyelashes. Furthermore, affected individuals may exhibit small, abnormally formed nails.

The severity of hearing loss associated with KID syndrome typically is profound, although it can occasionally be less severe.

Inheritance:

KID syndrome usually follows an autosomal dominant inheritance pattern. This means that only one copy of the mutated gene in each cell is enough to cause the disorder. Sometimes, an affected person inherits the mutated gene from a parent who also has the condition. However, in most cases, the syndrome arises from new gene mutations in individuals with no prior family history of the disorder. Some families have exhibited a condition similar to KID syndrome with autosomal recessive inheritance. This means that both copies of the relevant gene in each cell must be mutated for the condition to manifest. The parents of individuals with an autosomal recessive condition each carry one copy of the mutated gene, but generally do not show any signs or symptoms. Affected individuals in these families often present with liver disease, which is not a characteristic of the autosomal dominant form of KID syndrome. This autosomal recessive form is sometimes called Desmons syndrome. Whether Desmons syndrome is also caused by GJB2 gene mutations is currently unknown.