Prurigo actínico familiar / Familial actinic prurigo

Polymorphous light eruption may be familial. it may be produced by actinic rays and thence its prevalence in very high areas where they abound. Patients, probably, have a greater sensitiveness to those rays due to lack of urocanic acid - a protective substance of the skin against sunlight which is a consequence of deficient protein ingestion, since the said substance is a derivative of histidine and this in turn a component of the proteinic molecule. This explains why this disease is almost exclusive of the poor people. The relative indemnity of adult males is propably due to the better utilization of the few proteins of their diets as a consequence of the anabolic action of testosterone.