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Background: Non-hereditary colorectal cancer (CRC) is a complex disorder resulting from the combination of genetic and non-genetic factors. Genome–wide association studies (GWAS) are useful for identifying such genetic susceptibility factors. However, the single loci so far associated with CRC only represent a fraction of the genetic risk for CRC development in the general population. Therefore, many other genetic risk variants alone and in combination must still remain to be discovered. The aim of this work was to search for genetic risk factors for CRC, by performing single-locus and two-locus GWAS in the Spanish population. Results: A total of 801 controls and 500 CRC cases were included in the discovery GWAS dataset. 77 single nucleotide polymorphisms (SNP)s from single-locus and 243 SNPs from two-locus association analyses were selected for replication in 423 additional CRC cases and 1382 controls. In the meta-analysis, one SNP, rs3987 at 4q26, reached GWAS significant p-value (p = 4.02×10−8), and one SNP pair, rs1100508 CG and rs8111948 AA, showed a trend for two-locus association (p = 4.35×10−11). Additionally, our GWAS confirmed the previously reported association with CRC of five SNPs located at 3q36.2 (rs10936599), 8q24 (rs10505477), 8q24.21(rs6983267), 11q13.4 (rs3824999) and 14q22.2 (rs4444235). Conclusions: Our GWAS for CRC patients from Spain confirmed some previously reported associations for CRC and yielded a novel candidate risk SNP, located at 4q26. Epistasis analyses also yielded several novel candidate susceptibility pairs that need to be validated in independent analyses. [ABSTRACT FROM AUTHOR]

The MTHFD1L gene SNP variant rs11754661 was found to increase the risk of Alzheimer's disease in a recent Whole Genome Association Study [1]. We have carried out an independent study of this genetic variant in 2467 individuals from Spain. We found no evidence of association between the MTHFD1L marker and susceptibility to Alzheimer's disease in our sample. [ABSTRACT FROM AUTHOR]

GOLPH2 gene SNP variants Rs10868366 and Rs7019241 were reported to decrease the risk of Alzheimer's disease in a recent Whole Genome Association Study. We have investigated these genetic variants in 2470 individuals from Spain to conduct an independent replication study of the proposed SNP markers. We found no evidence of association between GOLPH2 markers and susceptibility to Alzheimer's disease in our series. We concluded that GOLPH2 gene does not contribute to risk of disease in this study sample. [ABSTRACT FROM AUTHOR]