In the last few years there have been rapid advances in developing genetic maps for humans, greatly enhancing our ability to localize and identify genes for inherited disorders. Through the collaborative efforts of three large groups generating microsatellite markers and the efforts of the 110 CEPH collaborators, a comprehensive human linkage map is presented here. It consists of 5840 loci, of which 970 are uniquely ordered, covering 4000 centimorgans on the sex-averaged map. Of these loci, 3617 are polymerase chain reaction-formatted short tandem repeat polymorphisms, and another 427 are genes. The map has markers at an average density of 0.7 centimorgan, providing a resource for ready transference to physical maps and achieving one of the first goals of the Human Genome Project--a comprehensive, high-density genetic map.

This study provides insight into the architecture of common genetic variation contributing to CRC etiology and improves risk prediction for individualized screening.

Background & Aims Known Genetic factors explain only a small fraction of genetic variation in colorectal cancer (CRC). We conducted a genome-wide association study (GWAS) to identify risk loci for CRC. Methods This discovery stage included 8027 cases and 22577 controls of East-Asian ancestry. Promising variants were evaluated in studies including as many as 11044 cases and 12047 controls. Tumor-adjacent normal tissues from 188 patients were analyzed to evaluate correlations of risk variants with expression levels of nearby genes. Potential functionality of risk variants were evaluated using public genomic and epigenomic databases. Results We identified 4 loci associated with CRC risk; P values for the most significant variant in each locus ranged from 3.92×10−8 to 1.24×10−12: 6p21.1 (rs4711689), 8q23.3 (rs2450115, rs6469656), 10q24.3 (rs4919687), and 12p13.3 (rs11064437). We also identified 2 risk variants at loci previously associated with CRC: 10q25.2 (rs10506868) and 20q13.3 (rs6061231). These risk variants, conferring an approximate 10%–18% increase in risk per allele, are located either inside or near protein-coding genes that include TFEB (lysosome biogenesis and autophagy), EIF3H (initiation of translation), CYP17A1 (steroidogenesis), SPSB2 (proteasome degradation), and RPS21 (ribosome biogenesis). Gene expression analyses showed a significant association (P <.05) for rs4711689 with TFEB, rs6469656 with EIF3H, rs11064437 with SPSB2, and rs6061231 with RPS21. Conclusions We identified susceptibility loci and genes associated with CRC risk, linking CRC predisposition to steroid hormone, protein synthesis and degradation, and autophagy pathways and providing added insight into the mechanism of CRC pathogenesis.

Genetic susceptibility to colorectal cancer is caused by rare pathogenic mutations and common genetic variants that contribute to familial risk. Here we report the results of a two-stage association study with 18,299 cases of colorectal cancer and 19,656 controls, with follow-up of the most statistically significant genetic loci in 4,725 cases and 9,969 controls from two Asian consortia. We describe six new susceptibility loci reaching a genome-wide threshold of P<5.0E-08. These findings provide additional insight into the underlying biological mechanisms of colorectal cancer and demonstrate the scientific value of large consortia-based genetic epidemiology studies.

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