Chromosome 2: The second largest chromosome in the human genome. Chromosome 2 contains over 240 million base pairs and more than 2500 genes, including the ETM2 gene for essential tremor, the MSH2 and MSH6 genes for colon cancer, and the PAX3 gene for Waardenburg syndrome.
Among the genes involved in colorectal cancer are MSH2 and MSH6 on chromosome 2 and MLH1 on chromosome 3. The protein products of these genes normally help repair mistakes made in DNA replication. If the MSH2, MSH6, and MLH1 proteins are mutated, the replication errors are not repaired, leading to damaged DNA and colon cancer.
Pax3 is one of a family of Pax genes involved in regulating embryonic development at the level of transcription. Mutation of Pax3 leads to Waardenburg syndrome with a wide bridge of the nose; pigmentary disturbances such as two different colored eyes, white forelock and eyelashes and premature graying of the hair; and some degree of nerve deafness.