LAS VEGAS – Hyperlinearity in the palms of atopic dermatitis patients may indicate filaggrin deficiency, which increases the likelihood of more severe and persistent disease and associated problems, according to Dr. Jacob Thyssen of the National Allergy Research Centre at Copenhagen University.
"If you can’t genotype" the filaggrin gene to check for mutations that decrease or eliminate the protective skin barrier protein, "check the palms of your patients and their parents" for deeper, more numerous, and slightly erythematous lines, said Dr. Thyssen. "I do that routinely. It’s harder in children, but it gets easier as they age," he said at the Skin Disease Education Foundation’s annual Las Vegas Dermatology Seminar.
Dr. Jacob Thyssen
When such lines are present, it’s probably a good idea to tell patients they may have a more severe case of atopic dermatitis and need to follow treatments and advice carefully, he said.
Filaggrin mutations were first identified in 2006 as the cause of ichthyosis vulgaris – a related condition associated with palm and plantar hyperlinearity – plus keratosis pilaris and fissured, dry, and scaly skin. The mutations have since been identified in about half of all severe atopic dermatitis patients, and risk of the disease increases 150-fold in homozygous mutation carriers who produce no filaggrin at all. Perhaps 10% of people of European ancestry carry filaggrin mutations, and it is less common in people of Asian or African descent, Dr. Thyssen noted.
"The filaggrin deficient group needs emollients," perhaps more so than other atopic dermatitis patients, and may benefit less from anti-inflammatory treatments, he said. "Barrier restoration [with hypoallergenic emollients] should be the main issue," he emphasized.
Moisturizers with ceramides and filaggrin breakdown products haven’t been heavily promoted in Europe. Although they may be effective, at this point "we just try to use very lipid-rich emollients," Dr. Thyssen said.
Filaggrin mutations in atopic dermatitis patients have been associated with allergic rhinitis and asthma, Dr. Thyssen said. Deficient patients also may be more susceptible to sun sensitivity, skin dehydration, skin infections, food allergies, and. contact dermatitis. The reason for these associations remains unclear; perhaps allergens have an easier time penetrating the skin and engaging the immune system when filaggrin is lacking, he said. Patients also seem to self-select for careers that avoid skin irritants such as nickel, he added.
Research is ongoing to devise treatments that directly correct the deficiency. However, it is likely that atopic dermatitis represents "many diseases with one face," said Dr. Thyssen. "Today, we treat all cases the same, but we are beginning to dissect" the various factors at play in individuals, and may one day be able to individualize treatment approaches, he said.
Dr. Thyssen had no relevant disclosures.
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