Large-scale population-based study shows no association between common polymorphisms of the TGFB1 gene and BMD in women.
The TGFB1 gene is a strong functional candidate for regulating genetic susceptibility to osteoporosis. We studied five common polymorphisms of TGFB1 in relation to osteoporosis-related phenotypes in a population-based cohort of 2975 British women, but found no significant association with bone mass, bone loss, bone markers, or fracture.


BACKGROUND
The gene encoding TGFB1 is a strong functional candidate for genetic susceptibility to osteoporosis. Several polymorphisms have been identified in TGFB1, and previous work has suggested that allelic variants of TGFB1 may regulate BMD and susceptibility to osteoporotic fracture.


METHODS
We studied the relationship between common polymorphisms of TGFB1 and several osteoporosis-related phenotypes including BMD at the lumbar spine and femoral neck, measured by DXA; bone loss over a 6-year period; biochemical markers of bone turnover (urinary free deoxypyridinoline and free pyridinoline/creatinine ratio and serum N-terminal propeptide of type 1 collagen), and fractures in a population-based study of 2975 women from the United Kingdom. Participants were genotyped for single nucleotide polymorphisms (SNPs) in the TGFB1 promoter (G-800A; rs1800468; C-509T; rs1800469), exon 1 (T29C; rs1982073 and G74C; rs1982073); and exon 5 (C788T; rs1800471) on PCR-generated fragments of genomic DNA. Haplotypes were constructed from genotype data using the PHASE software program, and genotypes and haplotypes were related to the phenotypes of interest using general linear model ANOVA, with correction for confounding factors including age, height, weight, menopausal status, hormone replacement therapy (HRT) use, physical activity score, and dietary calcium intake.


RESULTS
The polymorphisms were in strong linkage disequilibrium, and four common haplotypes accounted for >95% of alleles at the locus. There was no association between individual SNPs and BMD, bone loss, or biochemical markers of bone turnover. Haplotype analysis showed a nominally significant association with femoral neck BMD (p = 0.042) and with incident osteoporotic fracture (p = 0.013), but these were not significant after correcting for multiple testing.


CONCLUSIONS
Common polymorphic variants of the TGFB1 gene did not influence BMD or bone loss in this population.
McGuigan
Fiona E A
FE
Department of Medicine and Therapeutics, University of Aberdeen, UK. Fiona.McGuigan@med.lu.se
Macdonald
Helen M
HM
Bassiti
Amelia
A
Farmer
Rosemary
R
Bear
Stuart
S
Stewart
Alison
A
Black
Alison
A
Fraser
William D
WD
Welsh
Findlay
F
Reid
David M
DM
Ralston
Stuart H
SH
D015502:Absorptiometry, Photon; D001483:Base Sequence; D015519:Bone Density / Q000235:genetics*; D015331:Cohort Studies; D017931:DNA Primers; D005260:Female; D006801:Humans; D011110:Polymorphism, Genetic; D011159:Population Surveillance; D012606:Scotland; D016212:Transforming Growth Factor beta / Q000235:genetics*
D017931:DNA Primers; D016212:Transforming Growth Factor beta