[Familial aggregation of psoriasis].

Eight hundred and eight patients with psoriasis, 490 males and 318 females, what was 64% of all the patients with psoriasis in the region of Karlovac on June 30, 1991, were included in the study. The family onset rate of the disease was 33.3% and psoriasis occurred most frequently among first-degree relatives. The distribution of psoriasis between brothers and sisters of our patients was 8.09%. If the parents were affected with the disease, the percentage of brothers and sisters, with psoriasis increased proportionally. The risk of psoriasis among fraternal relatives is 25.7% according to Weinberg. These findings suggest that psoriasis is determined by genetic factors. The age of onset of psoriasis was analyzed with respect to familial occurrence. It was found that patients with psoriatic relatives had a 10-year earlier onset of the disease, particularly females, compared to those with negative history. By 25 years of age, 58% of the patients with positive and 35% with negative history were affected with the disease. These observations are consistent with the reports of some authors that an earlier onset of the disease announces familial frequency.