The objective of this study is to investigate G2350A polymorphism distribution of the ACE gene of ball game players as well as to analyze the effect of genetic polymorphism on the cardiovascular function of these subjects.
The result of investigating left ventricular mass index (LVmassI) and frequency of left ventricular hypertrophy (LVH) of ball game players such as soccer, baseball, basketball, volleyball and ice hockey, all the ball game players studied showed higher LVmassI value and higher LVH in average than those of the control group. This can be interpreted as result of change in cardiac structure and function caused by adaptation to intensive exercise taken by ball game players for a long period of time . Also, although no statistical significance has been observed, the basketball players and ice hockey players showed higher LVmassI value than players of other ball games, but basketball players showed the highest frequency of LVH as well. This result is because of different exercise methods between ball games which causes the cardiac structure and function to show different adaptive aspects. That is to say, it seems that the players of ball games such as basketball and ice hockey where fierce body fighting and body contact take place show larger change in adaptive aspect of cardiac structure and function to physical exercise than players of other ball games.
As ACE gene has long been attracting public attention as a genetic predisposition which affects cardiac structure and function such as LVH, many genetic epidemiological studies have been performed, and especially studies to investigate association of I/D polymorphism existing in this gene with cardiac structure and function have been globally performed with diverse groups including athlete groups as subjects. In most of these studies executed with patients of cardiovascular disease as subjects, as well as athletes who mainly take aerobic exercise and athletes who mainly take resistant exercise, it was reported that all showed significant association with change in cardiac structure and function caused by physical exercise [4, 6, 16–20, 24, 25].
However, although I/D polymorphism of ACE gene is associated with genetic linkage, it has been well unknown actual genetic effect . Therefore, we believe it is required to develop other new genetic markers which can exercise actual effect in this gene. Moreover, as various single nucleotide polymorphisms (SNP) in ACE gene are found to have more powerful effect of regulating serum ACE level than the I/D polymorphism, it will be very interesting to perform a study to analyze clinical association using G2350A polymorphism of ACE gene as the genetic marker .
Up to now, the first study result which analyzed clinical influence of G2350A polymorphism of ACE gene was the study performed by Mshmood et al., (2003), which analyzed association of G2350A polymorphism with essential hypertension with United Arab Emirates (UAE) population as subjects, where they reported that this genetic polymorphism showed significant association with essential hypertension . Also, though Iqbal et al., (2004) analyzed whether this genetic polymorphism showed significant association with myocardial infarction with Pakistan population as subjects, they could not detect any significant association . In relation to cardiac structure and function, Saeed et al., (2005) also analyzed association of this genetic polymorphism with left ventricular mass (LVH) using UAE population as subjects. As a result they reported significant association of this genetic polymorphism with LVH . Furthermore, in the study performed by Pan et al., (2007) with Chinese population as subjects, we suggested that G2350A polymorphism of ACE gene may affect change in cardiac structure and function shown for athlete group. It showed significant association with LVH appearing as a complication caused by essential hypertension, though this genetic polymorphism did not show any significant association with essential hypertension .
Nevertheless, to our knowledge, as there is no particular result of study on the influence of G2350A polymorphism on change in cardiac structure and function appearing to athlete group because there has not been much genetic epidemiological study on G2350A polymorphism of ACE gene in comparison to I/D polymorphism, we analyzed what influence G2350A polymorphism of ACE1 gene has on the change in cardiac structure and function of ball game players.
The result of comparing frequency of genotypes and allele consisting G2350A polymorphism of ACE gene of the control group and ball game players participating in this study showed that the genotype frequency observed was in Hardy-Weinberg equilibrium.
However, when frequency of genotypes and allele of G2350A polymorphism of this gene of the control group and ball game players participating in this study was compared, the result showed no significant difference in frequency of two groups and of each ball game players. Also, in this study, analysis was performed to examine what influence G2350A polymorphism of ACE gene has on cardiovascular risk factors such as echocardiographic data and serum biochemical parameters of the groups. No statistically significant association has been observed in both groups. There are some possibilities and limitations that G2350A polymorphism of ACE gene was not correlated with athletic performance ability in this study.
One possibility may be interpreted as the difference among ethnic groups. When frequency of A alleles which consist G2350A polymorphism of ACE1 gene was compared with frequency of A alleles of other healthy ethnic groups studied up to now, the frequency of A alleles of the participants of this study was 0.60 showing higher value than those of UAE population (0.37~0.38) of Pakistan population (0.32) and Chinese population (0.43) [10, 13~15]. However, our study with Korean population as subjects did not show any significant genetic association with cardiac structure and function of ball game players. Therefore, we think that further study is required to be performed with other ethnic groups as subjects.
Other limitations could be caused by the number of participants and diversity of athletics. In this study, we composed of 35 controls and 50 ball game player. More participants may be required for this subject to get statistical significance. We also recruited single athletic players in this study. We need to perform to check whether genetic polymorphism of this gene has any significant association with cardiac structure and function of athletes who take aerobic exercise such as long distance running or marathon and athletes who take resistant exercises such as wrestling or weight lifting. Actually, the I/D polymorphism of ACE gene is associated with endurance athletics such as marathon runner, longer distance swimmer [26, 27]. Therefore, we think that further study on athletes of various sporting disciplines is also required.