J Korean Acad Child Adolesc Psychiatry.  2007 Oct;18(2):123-129.

Family-Based Association Study of Tryptophan-2,3 Dioxygenase (TDO2) Gene and Autism Spectrum Disorder in the Korean Population

• Kim SA
• Park MR
• Cho IH
• Yoo HJ

Abstract

OBJECTIVES
Autism is a complex neurodevelopmental spectrum disorder with a strong genetic component. Previous neurochemical and genetic studies have suggested the possible involvement of the serotonin system in autism. Tryptophan 2,3-dioxygenase(TDO2) is the rate-limiting enzyme in the catabolism of tryptophan, which is the precursor of serotonin synthesis. The aim of this study was to investigate the association between the TDO2 gene and autism spectrum disorders(ASD) in a Korean population.
METHODS
The patients were diagnosed with ASD on the basis of the DSM-IV diagnostic classification outlined in the Korean version of the Autism Diagnostic Interview-Revised and Autism Diagnostic Observation Schedule. The present study included the detection of four single nucleotide polymorphisms(SNPs) in the TDO2 gene(rs2292536, rs6856558, rs6830072, rs6830800) and the family-based association analysis of the single nucleotide polymorphisms in Korean ASD trios using a transmission disequilibrium test(TDT) and haplotype analysis. The family trios of 136 probands were included in analysis. 87.5% were male and 86.0% were diagnosed with autism. The mean age of the probands was 78.5+/-35.8 months(range: 26-264 months).
RESULTS
Two SNPs showed no polymorphism, and there was no significant difference in transmission in the other two SNPs. We also could not find any significant transmission in the haplotype analysis(p>.05).
CONCLUSION
We could not find any significant statistical association between the transmission of SNPs in the TDO2 gene and ASD in a Korean population. This result may not support the possible involvement of the TDO2 gene in the development of ASD, and further exploration might be needed to investigate other plausible SNP sites.

Keyword

Autism Spectrum Disorders; Tryptophan 2,3-Dioxygenase(TDO2) Gene; Transmission Disequilibrium Test (TDT); Haplotype Analysis

MeSH Terms

Appointments and Schedules
Autistic Disorder*
Child
Autism Spectrum Disorder*
Classification
Diagnostic and Statistical Manual of Mental Disorders
Haplotypes
Humans
Male
Metabolism
Polymorphism, Single Nucleotide
Serotonin
Tryptophan
Serotonin
Tryptophan