An online catalogue of human genetic disorders and their genes, originally based on the book Mendelian Inheritance in Man by Victor McKusick and colleagues at Johns Hopkins University. It contains descriptions of human inherited diseases, along with the chromosomal location(s) of causative genes and links to sequence data where known. The database is provided and updated by the US National Center for Biotechnology Information (NCBI). Each entry has a unique six-digit MIM number, with allelic variants denoted by a four-digit suffix following a decimal point.