Maturity-onset diabetes of the young caused by a balanced translocation where the 20q12 break point results in disruption upstream of the coding region of hepatocyte nuclear factor-4alpha (HNF4A) gene.
Monogenic human disorders have been used as paradigms for complex genetic disease and as tools for establishing important insights into mechanisms of gene regulation and transcriptional control. Maturity-onset diabetes of the young (MODY) is a monogenic dominantly inherited form of diabetes that is characterized by defective insulin secretion from the pancreatic beta-cells. A wide variety of mutation types in five different genes have been identified that result in this condition. There have been no reports of a chromosome deletion or translocation resulting in MODY. We report a pedigree where MODY cosegregates with a balanced translocation [karyotype 46, XX t(3;20) (p21.2;q12)]. The chromosome 20 break point, 20q12, is within the region of one of the known MODY genes, hepatocyte nuclear factor-4alpha (HNF4A). Fluorescence in situ hybridization analysis demonstrated that the break point does not disrupt the coding region of this gene, but it lies at least 6 kb upstream of the conventional promoter (P1). We propose that this mutation disrupts the spatial relationship between the recently described alternate distal pancreatic promoter (P2) and HNF4A. This is the first case of MODY due to a balanced translocation, and it provides evidence to confirm the crucial role of an upstream regulator of HNF4A gene expression in the beta-cell.
Gloyn
Anna L
AL
Department of Diabetes and Vascular Medicine, School of Postgraduate Medical and Health Sciences, University of Exeter, Barrack Road, Exeter EX2 5AX, U.K.
Ellard
Sian
S
Shepherd
Maggie
M
Howell
Rodney T
RT
Parry
Elizabeth M
EM
Jefferson
Andrew
A
Levy
Elaine R
ER
Hattersley
Andrew T
AT
D000293:Adolescent; D000328:Adult; D000367:Age Factors; D051778:Basic Helix-Loop-Helix Leucine Zipper Transcription Factors; D002874:Chromosome Mapping; D002890:Chromosomes, Human, Pair 20; D004268:DNA-Binding Proteins; D003924:Diabetes Mellitus, Type 2 / Q000235:genetics*; D005260:Female; D051557:Hepatocyte Nuclear Factor 4; D006801:Humans; D007328:Insulin / Q000097:blood; D007621:Karyotyping; D010375:Pedigree; D010750:Phosphoproteins / Q000235:genetics*; D016133:Polymerase Chain Reaction; D018160:Receptors, Cytoplasmic and Nuclear / Q000235:genetics; D014157:Transcription Factors / Q000235:genetics*; D014178:Translocation, Genetic
D051778:Basic Helix-Loop-Helix Leucine Zipper Transcription Factors; D004268:DNA-Binding Proteins; C496592:HNF4A protein, human; D051557:Hepatocyte Nuclear Factor 4; D007328:Insulin; C403128:MLX protein, human; D010750:Phosphoproteins; D018160:Receptors, Cytoplasmic and Nuclear; D014157:Transcription Factors