Obesity and hyperinsulinemia in a family with pancreatic agenesis and MODY caused by the IPF1 mutation Pro63fsX60.
We studied the genetic and clinical features of diabetic subjects in a 5-generation Michigan-Kentucky pedigree ascertained through a proband with pancreatic agenesis and homozygous for the IPF1 mutation Pro63fsx60. Diabetic and nondiabetic family members were genotyped and phenotyped. We also carried out genetic studies to determine the history of the IPF1 mutation in the Michigan-Kentucky family and a Virginia family with the same mutation. We identified 110 individuals; 34 are currently being treated for diabetes and 10 of these are Pro63fsX60 carriers (ie, MODY4). Subjects with MODY as well as those with type 2 diabetes are characterized by obesity and hyperinsulinemia. Genetic studies suggest that the IPF1 mutation was inherited from an ancestor common to both the Michigan-Kentucky and Virginia families. MODY4 and type 2 diabetes in the Michigan-Kentucky pedigree are associated with obesity and hyperinsulinemia. Obesity and hyperinsulinemia have been observed occasionally in other subtypes of MODY, which suggests that hyperinsulinemia may be a general phenomenon when obesity occurs in MODY subjects. Hypoinsulinemia in nonobese MODY subjects seems to be caused by a functional defect in the beta cell. Genetic testing should be considered in multigenerational obese diabetic subjects, particularly when such families contain young diabetic members.
Fajans
Stefan S
SS
Department of Internal Medicine, Division of Metabolism, Endocrinology and Diabetes, University of Michigan Health System, Ann Arbor, MI 48105-9484, USA. sfajans@umich.edu
Bell
Graeme I
GI
Paz
Veronica P
VP
Below
Jennifer E
JE
Cox
Nancy J
NJ
Martin
Catherine
C
Thomas
Inas H
IH
Chen
Ming
M
D003924:Diabetes Mellitus, Type 2 / Q000235:genetics*; D005260:Female; D005786:Gene Expression Regulation / Q000502:physiology; D020022:Genetic Predisposition to Disease; D005838:Genotype; D018398:Homeodomain Proteins / Q000235:genetics* / Q000378:metabolism; D006801:Humans; D006946:Hyperinsulinism / Q000235:genetics*; D007231:Infant, Newborn; D007232:Infant, Newborn, Diseases / Q000235:genetics; D008297:Male; D009154:Mutation; D009765:Obesity / Q000235:genetics*; D010179:Pancreas / Q000002:abnormalities*; D010375:Pedigree; D015534:Trans-Activators / Q000235:genetics* / Q000378:metabolism
D018398:Homeodomain Proteins; D015534:Trans-Activators; C084010:pancreatic and duodenal homeobox 1 protein