Variation in the Gene for Muscle-Specific AMP Deaminase Is Associated With Insulin Clearance, a Highly Heritable Trait
- Mark O. Goodarzi12,
- Kent D. Taylor1,
- Xiuqing Guo1,
- Manuel J. Quiñones3,
- Jinrui Cui1,
- Xiaohui Li1,
- Tieu Hang1,
- Huiying Yang1,
- Edward Holmes4,
- Willa A. Hsueh3,
- Jerrold Olefsky5 and
- Jerome I. Rotter1
- 1Medical Genetics Institute, Departments of Pediatrics and Medicine, Steven Spielberg Pediatric Research Center, Cedars-Sinai Medical Center, Los Angeles, California
- 2Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine, Cedars-Sinai Medical Center, Los Angeles, California
- 3Division of Endocrinology, Diabetes, and Hypertension, Department of Medicine, David Geffen School of Medicine at UCLA, Los Angeles, California
- 4Department of Medicine, University of San Diego School of Medicine, San Diego, California
- 5Division of Endocrinology, Diabetes, and Hypertension, Department of Medicine, University of San Diego School of Medicine, San Diego, California
- Address correspondence and reprint requests to Mark O. Goodarzi, MD, PhD, Cedars-Sinai Medical Center, Division of Endocrinology, Diabetes and Metabolism, 8700 Beverly Blvd., Becker B-128, Los Angeles, CA 90048. E-mail: mark.goodarzi{at}cshs.org
Abstract
The rising prevalence of the insulin resistance syndrome in our society necessitates a better understanding of the genetic determinants of all aspects of insulin action and metabolism. We evaluated the heritability of insulin sensitivity and the metabolic clearance rate of insulin (MCRI) as quantified by the euglycemic-hyperinsulinemic clamp in 403 Mexican Americans. We tested the candidate gene AMP deaminase 1 (AMPD1) for association with insulin-related traits because it codes for an enzyme that has the potential to influence multiple aspects of insulin pharmacodynamics. By converting AMP to inosine monophosphate, AMPD1 plays a major role in regulating cellular AMP levels; AMP activates AMP kinase, an enzyme that modulates cellular energy and insulin action. We determined that nine AMPD1 single nucleotide polymorphisms (SNPs) defined two haplotype blocks. Insulin clearance was found to have a higher heritability (h2 = 0.58) than fasting insulin (h2 = 0.38) or insulin sensitivity (h2 = 0.44). The MCRI was associated with AMPD1 SNPs and haplotypes. Insulin clearance is a highly heritable trait, and specific haplotypes within the AMPD1 gene, which encodes a skeletal muscle−specific protein, are associated with variation in insulin clearance. We postulated that the processes of insulin action and insulin clearance in skeletal muscle are highly regulated and that AMPD1 function may play an important role in these phenomena.
- AMPK, AMP-activated protein kinase
- LD, linkage disequilibrium
- MCRI, metabolic clearance rate of insulin
- SNP, single nucleotide polymorphism
- TDT, transmission disequilibrium test
Footnotes
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- Accepted January 10, 2005.
- Received November 19, 2004.
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