title: PAX4 gene variations predispose to ketosis-prone diabetes.
abstract: Ketosis-prone diabetes (KPD) is a rare form of type 2 diabetes, mostly observed in subjects of west African origin (west Africans and African-Americans), characterized by fulminant and phasic insulin dependence, but lacking markers of autoimmunity observed in type 1 diabetes. PAX4 is a transcription factor essential for the development of insulin-producing pancreatic beta-cells. Recently, a missense mutation (Arg121Trp) of PAX4 has been implicated in early and insulin deficient type 2 diabetes in Japanese subjects. The phenotype similarities between KPD and Japanese carriers of Arg121Trp have prompted us to investigate the role of PAX4 in KPD. We have screened 101 KPD subjects and we have found a new variant in the PAX4 gene (Arg133Trp), specific to the population of west African ancestry, and which predisposes to KPD under a recessive model. Homozygous Arg133Trp PAX4 carriers were found in 4% of subjects with KPD but not in 355 controls or 147 subjects with common type 2 or type 1 diabetes. In vitro, the Arg133Trp variant showed a decreased transcriptional repression of target gene promoters in an alpha-TC1.6 cell line. In addition, one KPD patient was heterozygous for a rare PAX4 variant (Arg37Trp) that was not found in controls and that showed a more severe biochemical phenotype than Arg133Trp. Clinical investigation of the homozygous Arg133Trp carriers and of the Arg37Trp carrier demonstrated a more severe alteration in insulin secretory reserve, during a glucagon-stimulation test, compared to other KPD subjects. Together these data provide the first evidence that ethnic-specific gene variants may contribute to the predisposition to this particular form of diabetes and suggest that KPD, like maturity onset diabetes of the young, is a rare, phenotypically defined but genetically heterogeneous form of type 2 diabetes.
authors.affiliation: Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, Baylor College of Medicine, Houston, TX 77030, USA. fmjarvis@bcm.edu
authors.forename: Franck
authors.initials: F
authors.lastname: Mauvais-Jarvis
authors.forename: Stuart B
authors.initials: SB
authors.lastname: Smith
authors.forename: Cédric
authors.initials: C
authors.lastname: Le May
authors.forename: Suzanne M
authors.initials: SM
authors.lastname: Leal
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Gautier
authors.forename: Mariam
authors.initials: M
authors.lastname: Molokhia
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Riveline
authors.forename: Arun S
authors.initials: AS
authors.lastname: Rajan
authors.forename: Jean-Philippe
authors.initials: JP
authors.lastname: Kevorkian
authors.forename: Sumei
authors.initials: S
authors.lastname: Zhang
authors.forename: Patrick
authors.initials: P
authors.lastname: Vexiau
authors.forename: Michael S
authors.initials: MS
authors.lastname: German
authors.forename: Christian
authors.initials: C
authors.lastname: Vaisse
mesh_terms: D000354:Africa, Western; D019943:Amino Acid Substitution; D003922:Diabetes Mellitus, Type 1 / Q000235:genetics* / Q000378:metabolism; D003924:Diabetes Mellitus, Type 2 / Q000235:genetics* / Q000378:metabolism; D005786:Gene Expression Regulation / Q000502:physiology; D020022:Genetic Predisposition to Disease; D018398:Homeodomain Proteins / Q000235:genetics* / Q000378:metabolism; D006801:Humans; D007328:Insulin / Q000378:metabolism; D051761:Paired Box Transcription Factors; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism
chemical_list: D018398:Homeodomain Proteins; D007328:Insulin; C491709:PAX4 protein, human; D051761:Paired Box Transcription Factors; D014157:Transcription Factors