No evidence for involvement of polymorphisms of the dopamine D4 receptor gene in anorexia nervosa, underweight, and obesity

Family and twin studies suggest a genetic contribution to the etiology of a norexia nervosa (AN) and obesity. Genes involved in weight regulation can b e considered as candidate genes for AN. The dopaminergic system has been im plicated in weight regulation; previous results had suggested a possible in volvement of the dopamine D4 receptor gene (DRD4). We screened for alleles of two different polymorphisms (13-bp deletion, 48-bp repeat) in the DRD4. For association tests, allele frequencies were compared between 109 inpatie nts with AN, 82 underweight students, and 327 extremely obese children and adolescents. For application of transmission disequlibrium tests (TDT) we a dditionally genotyped 57 and 137 trios comprising a patient with AN or an e xtremely obese child or adolescent, respectively, and both parents. All gen otyping was performed with polymerase chain reaction fragment length polymo rphism analyses, None of the association tests or TDT rendered nominal P va lues below 0.1. An influence of alleles of the DRD4 on the development of A N, underweight, or extreme early onset obesity was not detected. Am. J. Med , Genet. (Neuropsychiatr. Genet.) 88:594-597, 1999. (C) 1999 Wiley-Liss, In c.