title: No association between TPH2 gene polymorphisms and ADHD in a UK sample.
abstract: Tryptophan Hydroxylase 2 (TPH2) is the rate-limiting enzyme in the biosynthesis of serotonin which is exclusively expressed in the brain. Recent molecular studies reported significant association between markers mapped to TPH2 and psychiatric conditions including ADHD. We have examined four single nucleotide polymorphisms (SNPs) two of which (rs1843809, rs1386493) were reported to associate with ADHD in an Irish ADHD sample. Transmission disequilibrium analysis revealed no significant association between any of these markers and ADHD. Dividing by the sex of the transmitting parent has also failed to replicate the previously reported paternal over-transmission of the associated alleles to ADHD probands. A larger sample size will be required to clarify if TPH2 alleles are or are not associated with ADHD.
authors.affiliation: Neuropsychiatric Genetics, Trinity Centre for Health Sciences, St. James' Hospital, Dublin 8, Ireland. sheehak@tcd.ie
authors.forename: Karen
authors.initials: K
authors.lastname: Sheehan
authors.forename: Ziarih
authors.initials: Z
authors.lastname: Hawi
authors.forename: Michael
authors.initials: M
authors.lastname: Gill
authors.forename: Lindsey
authors.initials: L
authors.lastname: Kent
mesh_terms: D000293:Adolescent; D000328:Adult; D001289:Attention Deficit Disorder with Hyperactivity / Q000235:genetics*; D001923:Brain Chemistry / Q000187:drug effects* / Q000235:genetics; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D004252:DNA Mutational Analysis; D005260:Female; D005819:Genetic Markers / Q000235:genetics; D020022:Genetic Predisposition to Disease / Q000235:genetics*; D005820:Genetic Testing; D006801:Humans; D040582:Inheritance Patterns / Q000235:genetics; D015810:Linkage Disequilibrium / Q000235:genetics; D008297:Male; D009154:Mutation / Q000235:genetics; D020641:Polymorphism, Single Nucleotide / Q000235:genetics*; D018401:Sample Size; D012701:Serotonin / Q000096:biosynthesis / Q000172:deficiency*; D012737:Sex Factors; D014365:Tryptophan Hydroxylase / Q000235:genetics*; D006113:United Kingdom
chemical_list: D005819:Genetic Markers; D012701:Serotonin; C494784:TPH2 protein, human; D014365:Tryptophan Hydroxylase