The relative roles of intragenic polymorphisms of the vitamin d receptor gene in lumbar spine degeneration and bone density.
METHODS
A retrospective cohort study.


OBJECTIVE
To compare the magnitudes of the associations of TaqI polymorphisms of the vitamin D receptor gene with bone density and lumbar spine degeneration in the same sample.


BACKGROUND
Vitamin D receptor gene variations are associated with osteoporosis, osteoarthritis, and disc degeneration. Their role in these conditions remains poorly understood.


METHODS
Bone density of the spine and femur were determined through DEXA, and lumbar disc degeneration was determined from magnetic resonance imaging assessments of signal intensity, disc narrowing, bulging, anular tears, herniations, and osteophytes. Associations between these measures and TaqI polymorphisms of the coding region of the Vitamin D receptor locus were examined in a population-based sample of 142 men.


RESULTS
The strongest associations were with signal intensity and anular tears, which were worse for the subjects with tt genotypes than for those with TT genotypes in the L4-S1 spine discs. Conversely, the prevalences of disc bulges and osteophytes were lowest for the tt genotype. Bone density, disc height, and herniations did not differ significantly by genotype.


CONCLUSIONS
The strongest association of Vitamin D receptor TaqI polymorphisms with degeneration in nonmineralized connective tissues suggests that the underlying mechanism of TaqI polymorphisms is not specific to bone. This study demonstrated for the first time that those with the tt genotype had more anular tears than those with the TT genotype, a finding that should stimulate further analyses of this gene in conditions that result in back pain. The apparent discrepancies of the associations of the tt genotype with lower signal intensity and more anular tears, but less bulges and osteophytes, could be explained if bulging and osteophytes primarily represented remodeling related to lifetime physical loading.
Department of Health Sciences, University of Jyväskylä, Jyväskylä, Finland. tapio.videman@ualberta.ca
T
T
Videman
L E
LE
Gibbons
M C
MC
Battié
K
K
Maravilla
E
E
Vanninen
J
J
Leppävuori
J
J
Kaprio
L
L
Peltonen
D000328:Adult; D000368:Aged; D015519:Bone Density / Q000235:genetics*; D015331:Cohort Studies; D015252:Deoxyribonucleases, Type II Site-Specific / Q000235:genetics*; D005260:Female; D005838:Genotype; D006801:Humans; D007403:Intervertebral Disc / Q000378:metabolism / Q000473:pathology* / Q000503:physiopathology; D007405:Intervertebral Disc Displacement / Q000235:genetics* / Q000378:metabolism / Q000503:physiopathology; D008159:Lumbar Vertebrae / Q000378:metabolism / Q000473:pathology* / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D010003:Osteoarthritis / Q000235:genetics / Q000378:metabolism / Q000503:physiopathology; D010024:Osteoporosis / Q000235:genetics / Q000378:metabolism / Q000503:physiopathology; D011110:Polymorphism, Genetic / Q000235:genetics*; D018167:Receptors, Calcitriol / Q000235:genetics* / Q000378:metabolism; D012189:Retrospective Studies; D013128:Spinal Osteophytosis / Q000235:genetics / Q000378:metabolism / Q000503:physiopathology; D018433:Twin Studies as Topic
D018167:Receptors, Calcitriol; D015252:Deoxyribonucleases, Type II Site-Specific; C027046:TCGA-specific type II deoxyribonucleases