myostatin polymorphisms in African Americans are associated with more muscle

**Dr Pangloss** · 04-23-2009, 05:53 PM

Tatyana, you were asking about this. This study (just came out) finds a couple polymorphisms in african americans are associated with greater muscle cross-section and greater strength. It doesnt seem to replicate in other races though....

1: Med Sci Sports Exerc. 2009 Apr 3. [Epub ahead of print] Links

Myostatin and Follistatin Polymorphisms Interact with Muscle Phenotypes and Ethnicity.

Kostek MA, Angelopoulos TJ, Clarkson PM, Gordon PM, Moyna NM, Visich PS, Zoeller RF, Price TB, Seip RL, Thompson PD, Devaney JM, Gordish-Dressman H, Hoffman EP, Pescatello LS.
1Department of Kinesiology, University of Connecticut, Storrs, CT; 2Department of Health Professions and Center for Lifestyle Medicine, University of Central Florida, Orlando, FL; 3Department of Exercise Science, University of Massachusetts, Amherst, MA; 4Division of Exercise Physiology, School of Medicine, West Virginia University, Morgantown, WV; 5Department of Sport Science and Health, Dublin City University, Dublin, IRELAND; 6Human Performance Laboratory, Central Michigan University, Mount Pleasant, MI; 7Department of Exercise Science and Health Promotion, Florida Atlantic University, Davie, FL; 8Division of Cardiology, Henry Low Heart Center, Hartford Hospital, Hartford, CT; 9Department of Diagnostic Radiology, Yale University School of Medicine, New Haven, CT; and 10Research Center for Genetic Medicine, Children's National Medical Center, Washington, DC.
PURPOSE:: We examined associations among myostatin (MSTN) 2379 A > G and 163 G > A and follistatin (FST) -5003 A > T and -833 G > T single nucleotide polymorphisms (SNP) on the muscle size and the strength response to resistance training (RT). METHODS:: Subjects (n = 645, age = 24.1 +/- 0.2 yr, body mass index [BMI] = 24.2 +/- 0.2 kg.m) self-disclosed themselves as Caucasian (78.9%), African American (3.6%), Asian (8.4%), Hispanic (5.0%), or Other (4.2%). They were genotyped for MSTN 2379 A > G (n = 645), MSTN 163 G > A (n = 639), FST -5003 A > T (n = 580), and FST -833 G > T (n = 603). We assessed dynamic (one repetition maximum [1RM]) and isometric (maximum voluntary contraction [MVC]) muscle strength and size (cross-sectional area [CSA]) of the elbow flexors before and after 12 wk of unilateral upper-arm RT. Repeated-measures ANCOVA tested associations among genetic variants and muscle phenotypes with age and BMI as covariates. RESULTS:: Baseline MVC was greater among African Americans who were carriers of the MSTN G allele (AG/GG, n = 15) than the A2379A homozygotes (n = 8; 64.2 +/- 6.8 vs 49.8 +/- 8.7 kg). African Americans who were carriers of the FST T allele (n = 12) had greater baseline 1RM (11.9 +/- 0.7 vs 8.8 +/- 0.5 kg) and CSA (24.4 +/- 1.3 vs 19.1 +/- 1.2 cm) than African Americans with the A-5003A genotype (n = 14; P < 0.05). No MSTN or FST genotype and muscle phenotype associations were found among the other ethnic groups (P >/= 0.05). CONCLUSION:: MSTN 2379 A > G and FST -5003 A > T were associated with baseline muscle strength and size among African Americans only. These ethnic-specific associations are hypothesis generating and should be confirmed in a larger sample of African Americans.

**Tatyana** · 04-23-2009, 06:00 PM

Interesting, I knew that myostatin polymorphisms had to have a lot to do with the variation in musculature.

Obviously it also shows up in some Caucasian populations, otherwise there wouldn't be the dominance you see in some power sports with some European countries.

**Dr Pangloss** · 04-23-2009, 06:09 PM

Originally Posted by Tatyana

Interesting, I knew that myostatin polymorphisms had to have a lot to do with the variation in musculature.

Obviously it also shows up in some Caucasian populations, otherwise there wouldn't be the dominance you see in some power sports with some European countries.

Yeah, i would not conclude for a second at this point that these same polymorphisms are only related to muscle in african americans. There are undoubtedly other factors, and it could also be a weakness in the study.