Phenotypes in OMIM include single gene Mendelian disorders (e.g., Marfan syndrome, achondroplasia, Huntington disease), traits (e.g. hair and eye color), susceptibility to drug reaction (e.g., malignant hyperthermia, warfarin sensitivity), altered susceptibility or reaction to infection (herpes simplex encephalitis, progression of HIV infection to AIDS), and germline susceptibility to cancer (e.g. BRCA1 and breast/ovarian cancer). Some recurrent deletion/duplication syndromes behave in a Mendelian fashion (e.g. Smith-Magenis and Potocki-Lupski syndromes), and OMIM has been expanding this category of entries. Some disorders that were thought to be caused by germline changes in DNA have turned out to present in the somatic mosaic state (e.g. McCune-Albirght syndrome or Proteus syndrome); these phenotypes for which a germline change would be lethal provide valuable insight into human gene function and disease pathophysiology. In this vein of understanding human disease processes, OMIM includes selected somatic mutations in cancers (e.g. the p.V660E mutation in BRAF, MIM:164757.0001) that are fundamental to our understanding of biology and medicine.
