D2 dopamine receptor Taq1A polymorphism, body weight, and dietary intake in type 2 diabetes.
OBJECTIVE
Certain D2 dopamine receptor Taq 1A genotypes (A1A1, A1A2) have been associated with obesity and substance abuse. We hypothesized that their presence would be associated with reduced efficacy of dietary interventions in individuals with type 2 diabetes.


METHODS
In the course of a randomized clinical trial in an outpatient research center in which 93 adults with type 2 diabetes were assigned to a low-fat vegan diet or a diet following 2003 American Diabetes Association guidelines for 74 wk, Taq 1A genotype was determined. Nutrient intake, body weight, and hemoglobin A1c (A1c) were measured over 74 wk.


RESULTS
The A1 allele was highly prevalent, occurring in 47% of white participants (n = 49), which was significantly higher than the 29% prevalence previously reported in non-diabetic whites (P = 0.01). The A1 allele was found in 55% of black participants (n = 44). Black participants with A1(+) genotypes had significantly greater mean body weight (11.2 kg heavier, P = 0.05) and greater intake of fat (P = 0.002), saturated fat (P = 0.01), and cholesterol (P = 0.02) compared with A2A2 (A1(-)) individuals; dietary changes during the study did not favor one genotype group. Among whites, baseline anthropometric and nutrient differences between gene groups were small. However, among whites in the vegan group, A1(+) individuals reduced fat intake (P = 0.04) and A1c (P = 0.01) significantly less than did A1(-) individuals.


CONCLUSIONS
The A1 allele appears to be highly prevalent among individuals with type 2 diabetes. Potential influences on diet, weight, and glycemic control merit further exploration.
Department of Medicine, George Washington University School of Medicine, Washington, D.C., USA. nbarnard@pcrm.org
Neal D
ND
Barnard
Ernest P
EP
Noble
Terry
T
Ritchie
Joshua
J
Cohen
David J A
DJ
Jenkins
Gabrielle
G
Turner-McGrievy
Lise
L
Gloede
Amber A
AA
Green
Hope
H
Ferdowsian
D001741:Black or African American / Q000235:genetics; D001835:Body Weight / Q000502:physiology*; D003924:Diabetes Mellitus, Type 2 / Q000178:diet therapy* / Q000453:epidemiology / Q000208:ethnology / Q000235:genetics*; D003927:Diet, Diabetic; D004038:Diet, Reducing; D014676:Diet, Vegetarian; D002149:Energy Intake / Q000502:physiology; D005260:Female; D005787:Gene Frequency; D005838:Genotype; D006442:Glycated Hemoglobin / Q000032:analysis; D006801:Humans; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000178:diet therapy / Q000453:epidemiology / Q000208:ethnology / Q000235:genetics; D011110:Polymorphism, Genetic; D017448:Receptors, Dopamine D2 / Q000235:genetics*; D016896:Treatment Outcome; D044465:White People / Q000235:genetics
D006442:Glycated Hemoglobin; D017448:Receptors, Dopamine D2