Haplotype-specific PCR for NAT2 diplotyping.

Area of Science:

• Pharmacogenetics and Molecular Diagnostics
• Biotechnology and Genetic Engineering

Background:

• N-acetyltransferase 2 (NAT2) enzyme activity varies significantly among individuals, influencing drug metabolism.
• NAT2 phenotypes (slow, intermediate, rapid acetylators) impact isoniazid efficacy and toxicity, crucial for tuberculosis treatment.
• Current NAT2 phenotyping relies on indirect statistical inference from SNP genotyping, lacking direct haplotype determination.

Purpose of the Study:

• To develop and validate a direct N-acetyltransferase 2 (NAT2) haplotyping method.
• To enable precise determination of NAT2 acetylator phenotypes for clinical pharmacogenetic applications.

Main Methods:

• Development of a novel haplotype-specific PCR (HS-PCR) assay targeting six common NAT2 haplotypes.
• Validation of the HS-PCR method by comparing results with sequencing in 650 Thai DNA samples.
• Analysis of diplotype concordance and identification of discrepancies.

Main Results:

• The HS-PCR method achieved a high concordance rate of 99.23% (645/650 samples) for NAT2 diplotype calls compared to sequencing.
• Discordant results were observed in 5 samples, attributed to three rare NAT2 haplotypes (NAT*5C, NAT2*7C, NAT2*11A).
• The method successfully identified rapid, intermediate, and slow acetylator phenotypes.

Conclusions:

• The developed HS-PCR method provides a direct and accurate means for NAT2 diplotyping.
• This novel technique facilitates the implementation of NAT2 phenotype determination in routine clinical pharmacogenetic testing.
• Direct NAT2 phenotyping can improve isoniazid dosage adjustments and patient outcomes in tuberculosis management.