title: Repeat variation in the human PER2 gene as a new genetic marker associated with cocaine addiction and brain dopamine D2 receptor availability.
abstract: Low dopamine D2 receptor (D2R) levels in the striatum are consistently reported in cocaine abusers; inter-individual variations in the degree of the decrease suggest a modulating effect of genetic makeup on vulnerability to addiction. The PER2 (Period 2) gene belongs to the clock genes family of circadian regulators; circadian oscillations of PER2 expression in the striatum was modulated by dopamine through D2Rs. Aberrant periodicity of PER2 contributes to the incidence and severity of various brain disorders, including drug addiction. Here we report a newly identified variable number tandem repeat (VNTR) polymorphism in the human PER2 gene (VNTR in the third intron). We found significant differences in the VNTR alleles prevalence across ethnic groups so that the major allele (4 repeats (4R)) is over-represented in non-African population (4R homozygosity is 88%), but not in African Americans (homozygosity 51%). We also detected a biased PER2 genotype distribution among healthy controls and cocaine-addicted individuals. In African Americans, the proportion of 4R/three repeat (3R) carriers in healthy controls is much lower than that in cocaine abusers (23% vs 39%, P=0.004), whereas among non-Africans most 3R/4R heterozygotes are healthy controls (10.5% vs 2.5%, P=0.04). Analysis of striatal D2R availability measured with positron emission tomography and [(11)C]raclopride revealed higher levels of D2R in carriers of 4R/4R genotype (P<0.01). Taken together, these results provide preliminary evidence for the role of the PER2 gene in regulating striatal D2R availability in the human brain and in vulnerability for cocaine addiction.
authors: Brookhaven National Laboratory, Medical Department, Center for Translational Neuroimaging, Upton, NY 11973, USA. eshumay@bnl.gov
authors: E
authors: E
authors: Shumay
authors: J S
authors: JS
authors: Fowler
authors: G-J
authors: GJ
authors: Wang
authors: J
authors: J
authors: Logan
authors: N
authors: N
authors: Alia-Klein
authors: R Z
authors: RZ
authors: Goldstein
authors: T
authors: T
authors: Maloney
authors: C
authors: C
authors: Wong
authors: N D
authors: ND
authors: Volkow
mesh_terms: D000328:Adult; D001741:Black or African American / Q000235:genetics; D000483:Alleles; D001213:Asian / Q000235:genetics; D019970:Cocaine-Related Disorders / Q000208:ethnology / Q000235:genetics*; D039301:Computers, Molecular; D003342:Corpus Striatum / Q000000981:diagnostic imaging / Q000378:metabolism*; D005260:Female; D005787:Gene Frequency / Q000235:genetics; D006580:Genetic Carrier Screening; D005819:Genetic Markers / Q000235:genetics*; D020022:Genetic Predisposition to Disease / Q000235:genetics*; D014644:Genetic Variation / Q000235:genetics*; D005828:Genetics, Population; D005838:Genotype; D006630:Hispanic or Latino / Q000235:genetics; D006720:Homozygote; D006801:Humans; D008297:Male; D018598:Minisatellite Repeats / Q000235:genetics; D056950:Period Circadian Proteins / Q000235:genetics*; D011110:Polymorphism, Genetic / Q000235:genetics; D049268:Positron-Emission Tomography; D017448:Receptors, Dopamine D2 / Q000235:genetics*; D044465:White People / Q000235:genetics
chemical_list: D005819:Genetic Markers; C421902:PER2 protein, human; D056950:Period Circadian Proteins; D017448:Receptors, Dopamine D2