J Korean Neuropsychiatr Assoc.  2004 Mar;43(2):151-158.

Effect of Homozygosity for 10-Repeat Allele at Dopamine Transporter Gene and Dopamine Transporter Density Assessed with [123I]IPT SPECT on Response to Methylphenidate Treatment in Attention Deficit Hyperactivity Disorder

• Cheon KA
• Ryu YH
• Kim JW

Abstract

OBJECTIVES
The symptoms of attention-deficit/hyperactivity disorder (ADHD) can be treated with methylphenidate, a potent blocker of the dopamine transporter (DAT). The homozygosity of the 10-repeat allele at dopamine transporter gene (DAT1) seems to be associated with a poor response to methylphenidate (MPH) in children with ADHD. In present study, we investigated association between DAT density using I-123N-(3-iodopropen-2-yl)-2beta-carbomethoxy-3beta-(4-chlorophenyl)tropane ([123I]IPT SPECT) and the homozygosity for 10-repeat allele at DAT1, and response to MPH in children with ADHD.
METHODS
Eleven drug-naive children with ADHD were included in the study and treated with MPH for about 8 weeks. After the genotyping and SPECT were performed, we compared DAT density between ADHD children with and without the homozygosity for the 10-repeat allele at DAT1 and investigated correlation between the homozygosity for the 10-repeat allele and response to MPH.
RESULTS
ADHD children with 10/10 genotype (n=7) had a significantly higher DAT density in basal ganglia than the children without 10/10 genotype (n=4)(Right: z=-2.65, p=0.008; Left: z=-2.65, p=0.008). We found that while only 28.6% (2/7) of the subject with 10/10 genotype showed good response (> or =50% improvement) to MPH treatment, 100% (4/4) of the subjects without 10/10 genotype showed good response to MPH treatment (chi2 test: F=5.238, df=1, p=0.022).
CONCLUSION
Our findings support an association between homozygosity for the 10-repeat allele at DAT1 and the DAT density assessed in vivo and correlation between the homozygosity for the 10-repeat allele and poor response to MPH.

Keyword

ADHD; Treatment response; Dopamine transporter gene; 10/10 genotype; Dopamine transporter density

MeSH Terms

Alleles*
Attention Deficit Disorder with Hyperactivity*
Basal Ganglia
Child
Dopamine Plasma Membrane Transport Proteins*
Dopamine*
Genotype
Humans
Methylphenidate*
Tomography, Emission-Computed, Single-Photon*
Dopamine
Dopamine Plasma Membrane Transport Proteins
Methylphenidate