Hereditary ichthyosis vulgaris is an autosomal dominant genetic disorder, which is a member of a group of cutaneous disorders of keratinization that appear similar both clinically and histologically. It is the most common form of ichthyosis, accounting for more than 95% of cases. The skin in hereditary ichthyosis vulgaris looks and feels normal at birth, but gradually becomes rough and dry in early childhood. Symptoms may include a dry and scaly skin, presence of small tile-like scales, flaky scalp, and deep painful cracks in the skin. Most cases of ichthyosis vulgaris are mild, but some cases are severe and can cover large areas of the body, including the abdomen, back, arms, and legs.
There is no cure for ichthyosis, but moisturizing and exfoliating the skin on a daily basis keeps the symptoms mild and manageable.
Mutations in the filaggrin (FLG) gene have been identified as the cause of ichthyosis vulgaris and was shown to be the major predisposing factor for atopic dermatitis. The encoded protein is important in functionally maintaining effective skin barrier. Two common FLG null mutations (p.R501X and c.2282del4) were identified in patients with ichthyosis vulgaris and they predispose to eczema and secondary allergic diseases. Patients carrying homozygous and compound heterozygous mutations may be severely affected, whereas heterozygotes showed mild disease or were asymptomatic, suggesting semidominant inheritance with incomplete penetrance in heterozygotes.