In this GWAs study, 10 664 genotyped single-nucleotide polymorphisms (SNPs) passed the quality control filtering in 371 German familial CRC patients and 1263 controls, and replication studies were conducted in four additional case-control sets (4915 cases and 5607 controls). We have observed that the risk of CRC increased significantly with an increasing number of risk alleles in seven genes involved in MAPK signalling events.