title: Studies of variations of the cyclin-dependent kinase inhibitor 1C and the cyclin-dependent kinase 4 genes in relation to type 2 diabetes mellitus and related quantitative traits.
abstract: CDK4 is involved in the regulation of body weight, pancreatic beta-cell proliferation, insulin responsiveness, and diabetes pathogenesis. CDK4 activity is inhibited by CDKN1C, which is regulated by insulin. In addition, CDKN1C plays an important role in beta-cell proliferation and is involved in the pathogenesis of the Beckwith-Wiedemann syndrome, a disorder characterized by neonatal hyperinsulinaemic hypoglycaemia and pre- and post-natal overgrowth. The aim of this study was to investigate if variations in the proximal promoter and the coding region of the CDKN1C and CDK4 genes are associated with type 2 diabetes or changes in related quantitative phenotypes among glucose-tolerant subjects. Mutation analyses of the two genes in 62 type 2 diabetic patients resulted in the discovery of seven variants of CDKN1C and two variants of CDK4. In a case-control study comprising 717 type 2 diabetic patients and 518 glucose-tolerant subjects the most frequent variants did not show any difference in allele frequencies between the type 2 diabetic patients and the control subjects. However, in two genotype-quantitative trait correlation studies involving 206 glucose-tolerant offspring of type 2 diabetic patients and 359 young, healthy subjects the CDKN1C del171APVA variant associated with increased birth weight (P=0.05 and P=0.05). Furthermore, the same variant tended to be associated with decreased basal glucose oxidation among 16 genotypically discordant dizygotic twins (P=0.03). In a genotype-quantitative trait study involving 500 middle-aged glucose-tolerant subjects the CDK4 IVS2-31G-->A variant was associated with an increased waist circumference (P=0.03) and waist-to-hip ratio (P=0.02) and altered fasting plasma glucose (P=0.03). However, these later findings could not be replicated in additional studies. In conclusion, variants in CDKN1C may contribute to the inter-individual variation in birth weight.
authors.affiliation: Steno Diabetes Center and Hagedorn Research Institute, Gentofte, Copenhagen, Denmark.
authors.forename: Eva-Maria D
authors.initials: EM
authors.lastname: Nielsen
authors.forename: Lars
authors.initials: L
authors.lastname: Hansen
authors.forename: Trine
authors.initials: T
authors.lastname: Stissing
authors.forename: Keiko
authors.initials: K
authors.lastname: Yanagisawa
authors.forename: Knut
authors.initials: K
authors.lastname: Borch-Johnsen
authors.forename: Pernille
authors.initials: P
authors.lastname: Poulsen
authors.forename: Allan
authors.initials: A
authors.lastname: Vaag
authors.forename: Torben
authors.initials: T
authors.lastname: Hansen
authors.forename: Oluf
authors.initials: O
authors.lastname: Pedersen
mesh_terms: D000368:Aged; D001724:Birth Weight / Q000235:genetics; D016022:Case-Control Studies; D051358:Cyclin-Dependent Kinase 4; D050761:Cyclin-Dependent Kinase Inhibitor p57; D018844:Cyclin-Dependent Kinases / Q000235:genetics*; D004252:DNA Mutational Analysis; D003718:Denmark; D003924:Diabetes Mellitus, Type 2 / Q000235:genetics*; D005260:Female; D014644:Genetic Variation; D005951:Glucose Tolerance Test; D006801:Humans; D007328:Insulin / Q000097:blood; D008297:Male; D008875:Middle Aged; D009687:Nuclear Proteins / Q000235:genetics*; D011110:Polymorphism, Genetic; D011401:Promoter Regions, Genetic; D011518:Proto-Oncogene Proteins / Q000235:genetics*; D019655:Quantitative Trait, Heritable; D012333:RNA, Messenger / Q000378:metabolism
chemical_list: C493964:CDKN1C protein, human; D050761:Cyclin-Dependent Kinase Inhibitor p57; D007328:Insulin; D009687:Nuclear Proteins; D011518:Proto-Oncogene Proteins; D012333:RNA, Messenger; C495900:CDK4 protein, human; D051358:Cyclin-Dependent Kinase 4; D018844:Cyclin-Dependent Kinases