Polymorphism C242T of the gene of the p22phox subunit for nicotinamide adenine dinucleotide phosphate oxidase, and erythrocytic antioxidant enzymes, in patients with tetralogy of Fallot.

Background: Nicotinamide adenine dinucleotide phosphate oxidase of the vascular cell membrane is an important source of reactive oxygen species. The aim of our study was to evaluate the possible influence of the p22phox C242T gene polymorphism on blood pressure and some markers of oxidative stress in children with tetralogy of Fallot.

Methods: After surgical repair in early life, we recruited 38 children, aged 11.7 plus or minus 3.2 years, including 185 healthy individuals as controls for the purposes of establishing frequencies of alleles and genotypes. From this latter group, we matched a sub-sample of 53 healthy caucasian children, aged 11.0 plus or minus 1.0 years, in order to compare enzymic activities.

Results: The children with tetralogy of Fallot showed significantly lower values of low-molecular-weight protein tyrosine phosphatase, particularly in carriers of CC genotype for the p22phox gene, with values of 145.2 plus or minus 77.4 micromol/g Hb/h, compared to controls, at 344.4 plus or minus 100.4 micromol/g Hb/h (p less than 0.001). Methemoglobin reductase activity in the patients with tetralogy was also lower in those with the CC genotype, at 9.8 plus or minus 3.2 micromol/g Hb-1 min(-1) compared to 24.2 plus or minus 11.8 micromol/g Hb(-1) min(-1) as measured in the controls (p less than 0.01). Lower systolic (p less than 0.05) and diastolic (p less than 0.01) blood pressures were also observed in the patients with tetralogy of Fallot.

Conclusions: Patients with tetralogy of Fallot having the CC genotype may be at a higher state of oxidative stress than T allele carriers, a finding which could have prognostic implications. Long term follow-up of these patients, however, may be necessary in order to draw definite conclusions.