Myostatin and follistatin polymorphisms interact with muscle phenotypes and ethnicity.
OBJECTIVE
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 x m(-2)) 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(2379) 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(-5003) 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(2)) 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 >or= 0.05).


CONCLUSIONS
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.
Kostek
Matthew A
MA
Department of Kinesiology, University of Connecticut, Storrs, CT 06269-2101, USA. Matthew.Kostek@gmail.com
Angelopoulos
Theodore J
TJ
Clarkson
Priscilla M
PM
Gordon
Paul M
PM
Moyna
Niall M
NM
Visich
Paul S
PS
Zoeller
Robert F
RF
Price
Thomas B
TB
Seip
Richard L
RL
Thompson
Paul D
PD
Devaney
Joseph M
JM
Gordish-Dressman
Heather
H
Hoffman
Eric P
EP
Pescatello
Linda S
LS
D000328:Adult; D000886:Anthropometry; D003430:Cross-Sectional Studies; D005006:Ethnicity / Q000208:ethnology*; D015444:Exercise; D038681:Follistatin / Q000235:genetics*; D006801:Humans; D008279:Magnetic Resonance Imaging; D018482:Muscle, Skeletal / Q000254:growth & development*; D055435:Myostatin / Q000235:genetics*; D020641:Polymorphism, Single Nucleotide / Q000235:genetics / Q000502:physiology*; D055070:Resistance Training; D055815:Young Adult
D038681:Follistatin; D055435:Myostatin