[Review for clinical molecular genetics of mutant insulin].

Three types of structurally abnormal insulin "Insulin Chicago, Los Angeles and Wakayama" has been identified in 6 families by the recent development of molecular biology. It has been clarified that a point mutation in the coding region of each patient's insulin gene allele give rise to a substitution of one amino acid of each insulin, resulting in reduced biological activities of these insulins. These abnormal insulin have slow metabolic clearance rate which cause typical hyperinsulinemia accompanying normal level of plasma C-peptide. In this paper, we review insulin gene mutations and discuss its participation to the pathogenesis of NIDDM.