The genetic epidemiology of tinea versicolor in China.

To study the clinical and epidemiological profile of Pityriasis versicolor (PV) and to determine the possible genetic model for PV in Chinese Han, we investigated 503 patients with PV who were recruited by a questionnaire method. Statistical analysis, heritability and complex segregation analysis were performed using EPI INFO 6.0, SPSS 10.0, the Falconer method and the SAGE-REGTL programs. In the total 503 PV patients, the mean age of onset was 22.85 +/- 10.36 years. For male and female patients, the peak ages of initial onset were both 20-29 years. A total of 106 (21.1%) patients were reported to have a positive family history of PV. The mean age of onset in males with positive family history was earlier than those with negative family history (t = 3.58, P < 0.01). Higher rate of recurrence and longer duration were seen in the patients with positive family history than those with negative family history. The heritability of PV in first-, second- and third-degree relatives was 48.13%, 40.11% and 27.20% respectively. Based on the REGTL results, the best model was a polygenic additive model for PV.