title: A novel A/G SNP in the -615th position of the dopamine D4 receptor promoter region as a source of misgenotyping of the -616 C/G SNP.
abstract: The polymorphic 5' upstream region of the dopamine D4 receptor (DRD4) gene containing several single nucleotide polymorphisms (SNPs) has recently become a focus of association studies in psychiatric genetics. Most SNP genotyping methods are based on the two-step procedure of restriction fragment length polymorphism (RFLP). An alternative technique is a single-step method of allele-specific amplification (ASA), previously introduced for genotyping the -521 C/T SNP of the DRD4 promoter region and applied here for the -616 C/G SNP. Parallel genotyping of individuals with the novel ASA method and the conventionally used Ava II RFLP showed a potential underestimation of the -616 GG genotype frequency by the conventional method. Sequencing the dubious samples clearly demonstrated a novel A/G SNP at the -615th position influencing the Ava II digestion and thus resulting in misgenotyping. To avoid this problem, we introduced the Sau96 I RFLP for the -616 C/G genotyping as this restriction enzyme is not sensitive for the -615 A/G sequence variation. Allele (-616 G = 0.48; -616 C = 0.52) and genotype (-616 GG = 0.25; -616 GC = 0.46; -616 CC = 0.29) frequencies were determined by both the novel ASA and the Sau96 I methods. The obtained genotype frequencies corresponded to the Hardy-Weinberg equilibrium in our healthy Caucasian sample (N = 534, P = 0.168). Using these methods, no association was found between the -616 C/G SNP and personality factors of Cloninger's temperament and character inventory (N = 153) in our population.
authors.affiliation: Institute of Medical Chemistry, Molecular Biology and Pathobiochemistry, Semmelweis University, Puskin u. 9, H-1088 Budapest, Hungary.
authors.forename: Z
authors.initials: Z
authors.lastname: Ronai
authors.forename: E
authors.initials: E
authors.lastname: Szantai
authors.forename: R
authors.initials: R
authors.lastname: Szmola
authors.forename: Z
authors.initials: Z
authors.lastname: Nemoda
authors.forename: A
authors.initials: A
authors.lastname: Szekely
authors.forename: J
authors.initials: J
authors.lastname: Gervai
authors.forename: A
authors.initials: A
authors.lastname: Guttman
authors.forename: M
authors.initials: M
authors.lastname: Sasvari-Szekely
mesh_terms: D005787:Gene Frequency; D020022:Genetic Predisposition to Disease; D005838:Genotype; D006801:Humans; D010551:Personality / Q000235:genetics*; D012150:Polymorphism, Restriction Fragment Length; D020641:Polymorphism, Single Nucleotide / Q000235:genetics*; D011401:Promoter Regions, Genetic / Q000235:genetics*; D017448:Receptors, Dopamine D2 / Q000235:genetics*; D050638:Receptors, Dopamine D4; D044465:White People
chemical_list: C493599:DRD4 protein, human; D017448:Receptors, Dopamine D2; D050638:Receptors, Dopamine D4