AUTISM AND THE SEROTONIN TRANSPORTER GENE
The role of the serotonin
transporter (5-HTT) in the development of neuropsychiatric disorders has been
widely investigated. A genetic research shed new light on its role (Conroy et al.
Serotonin transporter gene and autism: a haplotype analysis in an Irish
autistic population. Molecular Psychiatry 9, 587-593, June 2004). Two polymorphisms, an
insertion-deletion
in the promoter region and a 12 repeat allele in a variable
nucleotide tandem repeat (VNTR) in intron 2, drive higher expression of the
5-HTT gene. Four studies
have shown nominally significant excess
transmission of alleles of the 5-HTT gene in autism, while three studies have
reported no excess transmission. Conroy’s study investigates the role of 5-HTT in
the genetically homogenous Irish population. In all, 84 families were genotyped
for five polymorphisms.
The most significant haplotype associated with
transmission to affected probands was the SNP10VNTRSNP18 haplotype. This haplotype included the 12 repeat
allele of the VNTR, which is associated with increased expression and may play
a subtle role in the early development of the brain in affected probands.
BM&L-June 2004