Longitudinal changes in PON1 enzymatic activities in Mexican-American mothers and children with different genotypes...

Area of Science:

• Biochemistry
• Genetics
• Environmental Health

Background:

• Paraoxonase 1 (PON1) is crucial for preventing LDL oxidation and detoxifying organophosphate pesticides.
• Infants and children exhibit lower PON1 activity than adults, indicating reduced metabolic and antioxidant defenses.
• Genetic variability significantly influences PON1 phenotypes, impacting detoxification and oxidative stress responses.

Purpose of the Study:

• To longitudinally compare the influence of genetic variability on PON1 phenotypes in Mexican-American mothers and their children.
• To assess changes in PON1 activity from delivery to 7 years later in both mothers and children.
• To investigate the impact of pregnancy status on PON1 activity and its genetic control.

Main Methods:

• Longitudinal study design comparing mothers and children at delivery and 7 years later.
• Generalized estimating equations models used for statistical analysis.
• Analysis of five key PON1 polymorphisms (192, 55, -108, -909, -162) and their impact on enzyme activity.

Main Results:

• Children consistently showed lower mean PON1 activities than mothers at age 7.
• Children with specific low-activity genotypes (PON1(-108TT), PON1(192QQ), PON1(-909CC)) had a more pronounced activity difference.
• Mothers' PON1 activity was higher during pregnancy than when non-pregnant; genetic polymorphisms explained more activity variation in non-pregnant mothers.
• PON1 polymorphisms explained a larger proportion of paraoxonase activity variance (62-78%) compared to arylesterase activity (12.3-26.6%) in both groups.

Conclusions:

• Genetic control of PON1 activity differs between children and adults and is modulated by pregnancy status.
• Factors beyond known PON1 polymorphisms, including environmental, genetic, or epigenetic influences, likely contribute to PON1 expression variability.
• Understanding PON1 variability is critical for assessing susceptibility to organophosphate pesticides and oxidative stress, particularly in vulnerable populations like children.