c-MYC is a multifaceted protein that regulates cell proliferation, 
differentiation and apoptosis. Its crucial role in diverse cancers has been 
demonstrated in several studies. Here, we analysed the influence of the rare 
c-MYC Asn11Ser polymorphism on familial breast cancer risk by performing a 
case-control study with a Polish (cases n = 349; controls n = 441) and a German 
(cases n = 356; controls n = 655) study population. All cases have been tested 
negative for mutations in the BRCA1 and BRCA2 genes. A joint analysis of the 
Polish and the German study population revealed a 54% increased risk for breast 
cancer associated with the heterozygous Asn11Ser variant (OR = 1.54, 95% CI 
1.05-2.26, p = 0.028). The breast cancer risk associated with this genotype 
increases above the age of 50 years (OR = 2.24, 95% CI 1.20-4.21, p = 0.012). 
The wild-type amino acid Asn of this polymorphism is located in the N-terminal 
MYC transactivation domain and is highly conserved not only among most diverse 
species but also in the N-MYC homologue. Due to the pivotal role of c-MYC in 
diverse tumours, this variant might affect the genetic susceptibility of other 
cancers as well.