Myostatin Mutation Associated with Gross Muscle Hypertrophy in a Child
Schuelke M, Wagner KR, Stolz LE, et al.
Evidence is still limited and needs further study
Summary
A case report of a child who was extraordinarily muscular from birth. The child carried a loss-of-function mutation (in both alleles) of MSTN, the gene encoding myostatin — a hormone that brakes muscle growth — and had far more muscle mass and greater strength than peers. It was the first demonstration that inactivating myostatin causes gross muscle hypertrophy in humans, just as in double-muscled cattle (e.g. Belgian Blue) and 'mighty mice'. This is a single case (n=1) of a rare mutation and cannot be generalized to the wider population.
Key findings
- 1
A child with a loss-of-function mutation in MSTN (myostatin) was strikingly muscular from birth
- 2
Muscle mass and strength far exceeded those of same-age peers
- 3
Inactivating myostatin causes gross muscle hypertrophy in humans, as in double-muscled cattle and mice
- 4
A single case report (n=1) of a rare mutation; not generalizable to the population
Related research
Association of the ACTN3 R577X (rs1815739) polymorphism with elite power sports: A meta-analysis
PLoS One, 2019
A meta-analysis pooling 44 studies (~20,000 people: 4,850 elite power athletes and 15,903 controls). The R allele of ACTN3 — which encodes alpha-actinin-3, a protein in fast-twitch muscle fibers — was somewhat more common in elite power athletes (R allele odds ratio ≈1.20 [1.12–1.30]), and more clearly so in women (OR 1.58). The effect size is small, however, and elite athletes exist across every genotype. Genetics is only part of the predisposition to power and sprint performance, not a sole determinant of talent.
Upper limit of fat-free mass in humans: A study on Japanese Sumo wrestlers
American Journal of Human Biology, 1994
A study comparing body composition of 37 professional Sumo wrestlers, 14 bodybuilders, and 26 untrained men. Sumo wrestlers had significantly greater fat-free mass than bodybuilders; six exceeded 100 kg of fat-free mass, with a maximum of 121.3 kg (height 186 cm, weight 181 kg, 33.0% body fat). Although Sumo wrestlers had higher body fat (26.1% vs. 10.9% in bodybuilders), their fat-free mass (muscle, bone, etc.) beneath the fat was greater. The 'heavy-looking' physique's strength comes not from fat but from an enormous amount of fat-free mass. The authors suggested a fat-free mass / stature ratio around 0.7 kg/cm may be an upper limit in humans.
Articles featuring this study
Last checked: