Journal Article


Z Hawi
M Gill
M Fitzgerald
C Mullins
A Kirley
N Lowe
K Sheehan



genetics enzymology tph2 protein human attention deficit disorder with hyperactivity male tryptophan hydroxylase paternity genetic markers nuclear family ireland humans dna primers base sequence polymorphism single nucleotide genetic variation gene frequency female introns

Tryptophan hydroxylase 2 (TPH2) gene variants associated with ADHD. (2005)

Abstract Genetic and pharmacological studies have emphasised the role of serotonin 5-hydroxytryptamine (5-HT) as a possible etiologic factor in the development of attention-deficit hyperactivity disorder (ADHD). Tryptophan hydroxylase (TPH) is a rate-limiting enzyme in the biosynthesis of serotonin from tryptophan. Originally, the TPH gene was thought to be widely expressed, but a second form of TPH, TPH2, was recently identified and the TPH2 gene was found to be solely expressed in the brain. We examined eight single nucleotide polymorphisms (SNP) in the TPH2 gene for association with ADHD in 179 Irish nuclear families. Transmission disequilibrium test analysis revealed significant association between the T allele of marker rs1843809 with the disorder (chi2=12.2, P=0.0006, OR=2.36). Stratifying data by the sex of the transmitting parent showed that this association was enhanced when paternal transmission was considered (OR=3.7). In addition, several haplotypes (all including the associated marker) were associated with ADHD. These preliminary findings suggest that TPH2 is a susceptibility locus for ADHD. Further confirmation, preferably from different ethnic groups, is required to firmly implicate TPH2 in the pathophysiology of ADHD.
Collections Ireland -> Trinity College Dublin -> PubMed

Full list of authors on original publication

Z Hawi, M Gill, M Fitzgerald, C Mullins, A Kirley, N Lowe, K Sheehan

Experts in our system

Ziarih Hawi
Trinity College Dublin
Total Publications: 28
Michael Gill
Trinity College Dublin
Total Publications: 260
Michael Fitzgerald
Trinity College Dublin
Total Publications: 90