zhuangyh/Survival_Analysis

The incidence of malignant melanoma has been on the rise at an alarming rate in the United States and attracted great attention (1). The occurrence of melanoma is associated with race, skin color, skin tendency to burn, freckles, blue or green eye color, light hair color, family history, and prevalence of numerous melanocytic nevi (2-4). It has been shown that the presence of numerous melanocytic nevi is the strongest risk factor for melanoma. Nevi are likely to be precursor lesions for 20-60% of melanomas (5). White populations have higher risks for malignant melanoma than other racial/ethnic groups. In the United States, non-Hispanic white individuals had an annual incidence rate of 25.1 per 100 000 population for the period 2000 through 2004 compared with 1.0 per 100 000 for black, 4.5 per 100 000 for Hispanic white (1, 6). Two studies suggested heritability accounts for about 2/3 of the variance in nevus counts (7) (8). Several specific genetic variations have been implicated. The most notable genetic factors implicated in melanoma at present include CDKN2A, MC1R, and OCA2 (9). It has been shown that the OCA2 rs12913832 SNP is associated with Caucasian populations (10). OCA2 was also strongly related with hair color, with 36% of those homozygous for the g form (gg) having blonde hair compared to 8% of homozygotes for the  form (aa) (10). Given the strong relationship between nevus density and melanoma risk, melanoma risk genes are likely candidate genes for nevus formation. Thus, we hypothesized that OCA2 has association with nevus and that population with certain OCA2 variant are susceptible to developing nevus. To determine the influence of OCA2 on total nevus counts and changes on children, we also take gender and race into account in this study during estimating the effect of OCA2 on nevus development.

SAS