A TA-repeat polymorphism in the gene for the estrogen receptor alpha does not correlate with muscle strength or body composition in young adult Swedish women.
OBJECTIVE
There are conflicting data in the literature whether estrogens affect muscle strength. Prospective studies with hormone replacement therapy have not been able to convincingly demonstrate a muscular effect and the putative role of estrogen in the development of lean body mass is not established. Both lean mass and fat mass are known to be under strong genetic control and therefore we have investigated the relation between a TA-repeat in the gene for the estrogen receptor alpha (ERalpha) and muscle strength and body composition.


METHODS
175 healthy Swedish women, aged 20-39 were randomly selected from the population registry and included in the study. Body mass measurements (lean mass, fat mass, body weight and BMI) and muscle strength (quadriceps, hamstring and grip strength) were evaluated. The TA-repeat in the ERalpha gene was amplified by polymerase chain reaction.


RESULTS
Alleles with a TA-repeat length of 16 repeats or shorter were denoted short (e), and repeat length of 17 repeats or longer were denoted long (E). Women homozygous for the short and long genotype were denoted ee (31%) and EE (21%), respectively, while heterozygous individuals were denoted Ee (48%). The frequencies were in Hardy-Weinberg equilibrium. No associations were found between ERalpha genotypes and muscle strength or body composition.


CONCLUSIONS
The TA-repeat in the human ERalpha gene does not correlate with muscle strength or body mass measurements, indicating that body composition is not as sensitive to genetic variation in this receptor as other target organs for estrogen.
Grundberg
Elin
E
Department of Medical Sciences, Uppsala University Hospital, Uppsala SE-751 85, Sweden. elin.grunberg@medsci.uu.se
Ribom
Eva L
EL
Brändström
Helena
H
Ljunggren
Osten
O
Mallmin
Hans
H
Kindmark
Andreas
A
D000328:Adult; D001823:Body Composition / Q000502:physiology*; D018900:Dinucleotide Repeats; D047628:Estrogen Receptor alpha / Q000235:genetics*; D005260:Female; D005838:Genotype; D018737:Hand Strength / Q000502:physiology*; D006801:Humans; D018482:Muscle, Skeletal / Q000502:physiology*; D016133:Polymerase Chain Reaction; D011110:Polymorphism, Genetic; D013548:Sweden
D047628:Estrogen Receptor alpha