Vitamin D binding protein genotype is associated with serum 25-hydroxyvitamin D and PTH concentrations, as well as bone health in children and adolescents in Finland.
Vitamin D binding protein (DBP)/group-specific component (Gc), correlates positively with serum vitamin D metabolites, and phenotype influences serum 25-hydroxyvitamin D (S-25(OH)D) concentration. The protein isoform has been associated with decreased bone mineral density (BMD) and increased fracture risk. We examined the role of GC genotypes in S-25(OH)D status and BMD in 231 Finnish children and adolescents aged 7-19 yr. BMD was measured with DXA from lumbar spine (LS), total hip, and whole body, and for 175 subjects, radial volumetric BMD was measured with pQCT. Background characteristic and total dietary intakes of vitamin D and calcium were collected. The concentrations of 25(OH)D, parathyroid hormone (PTH), calcium and other markers of calcium homeostasis were determined from blood and urine. Genotyping was based on single-nucleotide polymorphism (rs4588) in the GC gene. The genotype distribution was: GC 1/1 68%, GC 1/2 26% and GC 2/2 6%. A significant difference emerged in 25(OH)D and PTH concentrations between the genotypes, (p = 0.001 and 0.028 respectively, ANCOVA). There was also a linear trend in: Gc 2/2 had the lowest 25(OH)D and PTH concentrations (p = 0.025 and 0.012, respectively). Total hip bone mineral content was associated with GC genotype (BMC) (p = 0.05, ANCOVA) in boys. In regression analysis, after adjusting for relevant covariates, GC genotype was associated with LS BMC and strength and strain index (SSI) Z-score in both genders, and LS BMD in boys. In conclusion, the present study demonstrates the association between GC genotypes and S-25(OH)D and PTH concentrations. The results show the influence of DBP genetic variation on bone mass accrual in adolescence.
Department of Food and Environmental Sciences, University of Helsinki, Helsinki, Finland ; Folkhälsan Institute of Genetics, Folkhälsan Research Center, Helsinki, Finland.
Minna
M
Pekkinen
Department of Food and Environmental Sciences, University of Helsinki, Helsinki, Finland.
Elisa
E
Saarnio
Children's Hospital, Helsinki University Central Hospital and University of Helsinki, Helsinki, Finland.
Heli T
HT
Viljakainen
Department of Food and Environmental Sciences, University of Helsinki, Helsinki, Finland.
Elina
E
Kokkonen
Division of Nutrition, National Food Institute, Technical University of Denmark, Soborg, Denmark.
Jette
J
Jakobsen
Department of Food and Nutritional Sciences, University College, Cork, Ireland.
Kevin
K
Cashman
Folkhälsan Institute of Genetics, Folkhälsan Research Center, Helsinki, Finland ; Children's Hospital, Helsinki University Central Hospital and University of Helsinki, Helsinki, Finland.
Outi
O
Mäkitie
Department of Food and Environmental Sciences, University of Helsinki, Helsinki, Finland.
Christel
C
Lamberg-Allardt
D000293:Adolescent; D000483:Alleles; D015519:Bone Density / Q000235:genetics*; D001842:Bone and Bones; D002136:Calcium, Dietary / Q000378:metabolism; D002648:Child; D005260:Female; D005387:Finland; D005838:Genotype; D006801:Humans; D008297:Male; D010281:Parathyroid Hormone / Q000097:blood* / Q000235:genetics / Q000378:metabolism; D020641:Polymorphism, Single Nucleotide / Q000235:genetics; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000097:blood / Q000235:genetics / Q000378:metabolism; D014809:Vitamin D-Binding Protein / Q000235:genetics* / Q000378:metabolism
D002136:Calcium, Dietary; D010281:Parathyroid Hormone; D014809:Vitamin D-Binding Protein; D014807:Vitamin D; C104450:25-hydroxyvitamin D