TH01, a tetrameric short tandem repeat locus in the tyrosine hydroxylase gene: association with myocardial hypertrophy and death from myocardial infarction?

TH01 is a tetrameric short tandem repeat locus located in intron 01 of the tyrosine hydroxylase gene. The tyrosine hydroxylase catalyzes the hydroxylation of L-tyrosine to L-DOPA and is the rate limiting enzyme in the synthesis of catecholamines like noradrenaline or adrenaline, which are pivotal in the regulation of blood pressure. In a clinical study a strong correlation between alleles *9.3 and *10 and essential hypertension was observed ([2] Hypertension 32: 676-682). To further investigate this association, we typed TH01 in 296 autopsy cases and correlated the genotypes to the heart weight as parameter for myocardial hypertrophy. No significant correlation was observed. Moreover, dividing the studied cases into 2 groups, one including 172 casualties from hypertension-associated diseases (myocardial infarction, left heart failure, aortic aneurysm, spontaneous intracerebral bleeding and cerebral infarction) and one consisting of 124 cases of death unrelated to hypertension, revealed similar allelic frequencies for both groups. Our data thus suggest that TH01 long alleles appear not to lead to a significant increase in the incidence of myocardial hypertrophy or other hypertension associated diseases. This could be explained by a relatively small impact of the TH01 genotype on the blood pressure or by counteraction of another mechanism related to catecholamines and their effect on the human body.