Scientists at deCODE genetics have report the discovery of common versions of two single-letter variations in the human genome (SNPs) that confer risk of basal cell carcinoma (BCC), the most common cancer among people of European ancestry. Unlike the four sets of SNPs previously found by deCODE to confer risk of BCC and cutaneous melanoma, those currently reported are not linked to fair pigmentation traits that also make certain people prone to freckling and sunburn.
These SNPs, both located on chromosome 1, may therefore provide new insight into an underlying biological mechanism causing BCC, independent of the impact of exposure to ultraviolet (UV) radiation in sunlight.
Approximately 2% of people of European descent carry two copies of the risk versions of both SNPs, and are at a 170% greater risk of BCC than those who do not carry the risk variants. The paper, entitled ‘Common variants on 1p36 and 1q42 are associated with cutaneous basal cell carcinoma but not with melanoma or pigrmentation traits,’ appears in the online edition of Nature Genetics.
“With this discovery we continue to build our portfolio of novel risk factors for common skin cancers, diseases that cause significant morbidity and that are on the rise in the industrialized world. Once again we have used our capabilities in human genetics to gain a new understanding of the root causes of a major disease, that appear to act independently of known environmental risk factors. These two SNPs can also be used to enable individuals to better understand their own susceptibility to BCC and thus to take measures to lower their environmental and overall risk, and we are pleased to have added them already to our deCODEme™ service,” said Kari Stefansson, CEO of deCODE and senior author of the study.
The SNPs were discovered through the analysis of more than 300,000 SNPs across the genomes of more than 900 Icelanders with BCC and more than 33,000 control subjects. The SNPs most strongly correlated with BCC were then validated through the analysis of additional Icelandic and Eastern European cohorts of approximately 4,000 cases and controls. The deCODE team then analyzed data from more than 42,000 individuals from Iceland, Sweden and Spain to demonstrate that these novel variants conferring risk of BCC do not correlate with either fair pigmentation or with risk of cutaneous melanoma.
The SNPs currently reported thus appear to confer risk independently of that of variants in or near the MC1R, ASIP, TYR and TYRP1 genes that deCODE has reported in earlier studies.
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