The cause of<unk>  is unknown but is presumed to be a combination of genetic and environmental factors. Environmental The hygiene hypothesis postulates that the cause of asthma, eczema, and other allergic diseases is an unusually clean environment in childhood which leads to an insufficient human microbiota. It is supported by epidemiologic studies for asthma. The hypothesis states that exposure to bacteria and other immune system modulators is important during development, and missing out on this exposure increases the risk for asthma and allergy. One systematic review of literature on eczema found that urban areas have an increased prevalence of eczema compared to rural areas. While it has been suggested that eczema may sometimes be an allergic reaction to the excrement from house dust mites, with up to 5% of people showing antibodies to the mites, the overall role this plays awaits further corroboration. Malnutrition Essential fatty acid deficiency results in a<unk>  similar to that seen in zinc or biotin deficiency. Genetic A number of genes have been associated with eczema, one of which is filaggrin. Genome-wide studies found three new genetic variants associated with eczema: OVOL1, ACTL9 and IL4-KIF3A. Eczema occurs about three times more frequently in individuals with celiac disease and about two times more frequently in relatives of those with celiac disease, potentially indicating a genetic link between the conditions.
Dermatitis
Psoriasis
Photokeratitis
Scabies
Keratitis
Dermatitis herpetiformis
Arthralgia
Lichen simplex chronicus