Angiotensin converting enzyme (ACE), Actinin (ACTN3), Tumour necrosis factor (TNF) gene polymorphism associated with biomarkers and physical characteristics in young African cricket players of Zulu origin

Dissertation submitted to the Department of Biochemistry and Microbiology, in the Faculty of Science and Agriculture at the University of Zululand (South Africa) in partial fulfilment of the requirements for the Masters (MSc) degree in Biochemistry, 2012.

Current research in biochemistry and genetics focuses on finding a relationship between genes and biomarkers that are playing a fundamental role in physical performance. A possible link between these genes, molecular adaptation to exercise training and various markers of physical performance has been established in the past decade. A handful of genes have been studied by scientists, among them are the Angiotensin Converting Enzyme (ACE), ACTN3 (Actinin) and the Tumor Necrosis Factor (TNF). The ACE gene which encodes the angiotensin converting enzyme has been studied in detail and is known for influencing human physical performance and trainability. ACTN3 gene encodes the actinin-3 protein, that is known to form part of the sarcomeric Z-line, anchoring the actin filaments together and maintaining the mechanical integrity of the muscles. The TNF gene is among less studied genes, it encodes the Tumor Necrosis Factor protein which initiates the production of interleukins and that results in the production of the inflammatory biomarker C- reactive protein (CRP). Cricket is like any other sport in whereby there are energy requirements, physical characteristics that have been accepted as indicators of good performance in the game (body mass index, hand grip, quadriceps and hamstring strength) which are assessed for the purpose of the study. This study therefore sought to explore the ACE I/D, ACTN3 R/X and TNF G/A gene polymorphism, biomarkers (uric acid (UA) lactate (LA) and CRP) changes and the association with physical tests in a previously unexplored cohort of African Zulu cricketers. The participants were 31 Africans males aged 20-27 years (n=14 cricketers and n=17 controls). The genotyping (blood spots) was performed by PCR amplification followed by restriction digestion. After ANOVA the association was examined using Chi2 maximum likelihood test and Fisher’s exact test. ACE genotyping for the whole group displayed a complete absence of II genotype, 67.7% DD and 32.3% ID genotypes. The frequency of D allele was 83.8% and I allele 16.2%. In cricketers DD and ID genotypes were 50% each compared to controls-83% DD and 17% ID. The D allele is associated with power/sprint performance and the I allele with endurance. ACTN3 genotype frequencies for the cohort were 90.3% RR and 9.7% RX. The XX genotype was absent. The R allele is linked to sports that require power/sprint and the X allele is related to endurance. No differences in genotype frequencies between the two groups were noted. R allele at extremely high frequency (100%) was associated with CRP (<3.0 mg/L) in cricketers (p=0.0001) and controls (p=0.0140). TNF genotyping displayed 42% GG, 45% GA and 13% AA for the whole cohort, but no differences between both groups. CRP (<3.0 mg/L) was associated (p=0.0001) with low A allele frequency (18% in controls and 40% in cricketers). Interestingly, a null homozygosis of both the ACE II and the ACTN3 XX genotypes was found for the first time in the cohort of Zulu cricketers. This research demonstrates high ACE D allele frequency and a strong ACTN3 R allele association with low CRP, UA and LA levels. This study provides evidence about the genotype distribution of previously unexamined cohort of African athletes.

National Research Foundation ) and the University of Zululand