Association Analysis of Two Tyrosine Hydroxylase Gene Polymorphisms in Normotensive Offspring from Hypertensive Families

Objective: We have studied possible association between predisposition to essential hypertension, plasma noradrenaline level and two polymorphisms of the gene for tyrosine hydroxylase (TH), the rate-limiting enzyme of catecholamine biosynthesis. Design and Methods: One hundred and one normotensive sons from normotensive parents (SN) and 107 normotensive sons of hypertensive families (SH) were studied. Tetranucleotide TCAT repeat and Val81Met polymorphisms of the TH gene were determined by polymerase chain reaction (PCR) technique. Results: SH had higher systolic BP and plasma noradrenaline concentration than the SN group. No significant difference was found between the allele and genotype frequencies in the SH and SN groups for both polymorphisms. The two polymorphisms were in tight linkage disequilibrium. The CD genotype of the microsatellite marker was associated with increased plasma noradrenaline concentration in both groups. Genotypes AB, AE and BB of the TCAT repeat polymorphism and genotypes VM and MM of the Val81Met polymorphism exhibited the greatest difference in plasma noradrenaline concentration between the SH and SN groups. Conclusion: The studied TH polymorphisms do not appear to be associated with family history of essential hypertension. Nevertheless, some genotypes of TH might be related to disturbance of plasma noradrenaline concentration.