REYKJAVIK, Iceland, May 18 In two papers published today,deCODE scientists and academic colleagues from Europe and the U.S. expand uponthe company's recent findings in the genetics of pigmentation traits in peopleof European descent, and demonstrate that certain of these common variantsalso confer risk of two types of skin cancer. In the first paper, utilizinggenomic analysis of nearly 8,500 Icelandic and Dutch participants, the deCODEteam identified a novel, tightly-linked pair of single-letter variants (SNPs)near the ASIP (agouti signaling protein) gene on chromosome 20 that greatlyincrease the likelihood of an individual being prone to freckles and sunburn.A SNP in the TYR (tyrosinase) gene on chromosome 11, previously linked bydeCODE to eye color, was here shown also to confer susceptibility to sunburn.Both ASIP and TYR are known to play a role in pigmentation.
Because very fair skin, blue or green eyes, freckles, red hair, andexposure to ultraviolet light are all known risk factors for skin cancer, inthe second paper the deCODE team set out to investigate whether the variantsit had linked to pigmentation traits also associated with risk of cutaneousmelanoma (CM) and basal cell carcinoma (BCC). CM is the most dangerous form ofskin cancer, while BCC is very common but does not frequently spread to otherparts of the body. In case-control and replication studies involving a totalof some 45,000 CM and BCC patients and control subjects from Iceland, Sweden,Spain, Hungary, Romania and Slovakia, carrying one set of the ASIP variants --which 15% of the population does -- was shown to correspond to a 45% increasein risk of CM and 33% increase in risk of BCC compared to non-carriers. Eachcopy of the TYR variant, of which 35% of people carry at least one copy, wasfound to confer a 20% increased risk of CM and a 14% increase in risk of BCCcompared to non-carriers. These increases in risk remain significant evenafter accounting for the effect of the pigmentation traits themselves oncancer risk. Furthermore, several other variants that deCODE has also linkedto freckling and sensitivity to sun did not show any detectable link to skincancer.
"It is common knowledge that people with fairer complexions tend to bemore sensitive to the sun, and that extensive exposure to sun or repeatedburning can increase the risk of skin cancers. But we are now showing thatthere are a variety of different genetic bases for what appear to be the samepigmentation characteristics, and we have demonstrated that certain of thesecarry with them greater risk of skin cancer than do others. This informationis important for understanding the biology of skin cancers, particularly as itappears that these variants may be conferring some of this additional riskthrough a mechanism independent of their role in giving rise to sun-sensitiveskin. These findings may also be useful for helping individuals to bettergauge their susceptibility to skin cancer, and we are therefore very pleasedto be including these variants in our deCODEme(TM) service," said KariStefansson, CEO of deCODE.
The papers, 'Two newly identified genetic determinants of pigmentation inEuropeans' and 'ASIP and TYR pigmentation variants associate with cutaneousmelanoma and basal cell carcinoma,' are published today in the online editionof Nature Genetics, at www.nature.com/ng, and will be published in an upcomingprint edition of the journal.
This research was supported in part by the Intramural Research Program ofthe National Institutes of Health, National Cancer Institute, Division ofCancer Epidemiology and Genetics, by a subcontract agreement to deCODEGenetics under Westat contract N02-CP-91026 to the National Cancer Institute.The Swedish portion of the study received financial support from the SwedishCancer Society, the Radiumhemmet Research Funds and the Swedish ResearchCouncil.