Improved method for the identification of the fluoride-resistant plasmacholinesterase genotypes

Area of Science:

• Biochemistry
• Human Genetics
• Pharmacogenetics

Background:

• Plasmacholinesterase (PChE) exhibits genetic variations affecting drug metabolism.
• Dibucaine and fluoride inhibition assays are used to identify PChE genotypes.
• Existing methods struggle to differentiate dibucaine-resistant from fluoride-resistant PChE variants.

Purpose of the Study:

• To modify the Harris and Whittaker method for improved differentiation of PChE genotypes.
• To establish a reliable assay for identifying fluoride-resistant PChE variants.

Main Methods:

• Modified the existing assay by increasing reaction temperature to 37°C and Na fluoride concentration to 2.5 x 10⁻⁴ M.
• Assessed Na fluoride (FN) inhibition in genetically normal and dibucaine-resistant heterozygote individuals.
• Analyzed the correlation between dibucaine (DN) and fluoride (FN) numbers.

Main Results:

• Genetically normal individuals showed a mean FN of 43.0 ± 10.0.
• Atypical dibucaine-resistant heterozygotes exhibited a mean FN of 67.0 ± 5.37.
• A linear correlation between DN and FN was observed, enabling distinct identification of the fluoride-resistant PChE genotype (Ef).

Conclusions:

• The modified method effectively distinguishes between dibucaine-resistant and fluoride-resistant PChE genotypes.
• This enhanced assay provides a more precise tool for PChE genetic profiling.
• Accurate identification of the Ef genotype is now achievable using the observed DN-FN correlation.