An autosomal irregularly dominant mode of inheritance for AECD in guinea pigs has been clearly demonstrated. A role for genetic factors in the development of the disorder in humans is suggested by an increased frequency of allergic diseases among relatives of patients who have allergic eczematous contact dermatitis. The incidence of positive patch-test reactions generally decreases with increasing age. On the other hand, in elderly patients, the course of AECD may be lengthened and the disease may be more resistant to therapy because of the increased skin dryness that normally accompanies advancing age. Because of its presence in costume jewelry, zippers, and clasps, nickel is one of the most common contact allergens among females, but not among males.
Acrylic nails are also a much more common contact allergen among females than among males.
Acrylic nails include nails repaired with silk or linen that is bonded with acrylic glue, plastic nails attached with acrylic glue, and sculptured nails formed by the shaping of acrylate polymers onto the nail plate. Wearing such nails can cause dermatitis, nail dystrophy, and traumatic onycholysis. Impeded evaporation results in the accumulation of moisture in the nail plate, which predisposes to bacterial and yeast infections. In addition, allergy to the acrylic glues may cause a dermatitis not only on the fingers but at distant skin sites as well. Nail dystrophy and even permanent nail loss may result.