[Association between Fok I vitamin D receptor (VDR) gene polymorphism and plasmatic concentrations of transforming growth factor-beta1 and interferon gamma in type 1 diabetes mellitus].
OBJECTIVE
In order to assess whether Fok I vitamin D receptor gene (VDR) polymorphism is involved in the genetic susceptibility of type 1 diabetes, a case-control study was conducted and VDR genotypes were related to serum concentrations of 25(OH) vitamin D and cytokines transforming growth factor beta1 (TGF-beta1) and interferon gamma (INF-gamma).


METHODS
151 incident cases of type 1 diabetes and 182 non related healthy controls from Santiago were studied for VDR polymorphisms in peripheral blood DNA. Exon 2 (Fok I) segments were amplified by polimerase chain reaction and analyzed by means of restriction fragment length polymorphism to determine each corresponding genotype. Differences for allele, genotype and serological markers as 25(OH) vitamin D, TGF-beta1 and INF-gamma levels distribution between patients and controls were analyzed.


RESULTS
Fok I polymorphism distribution analysis showed no differences between patients and controls. Among diabetics, higher levels of TGF-beta1 (median, 282.6 pg/ml; range, 131.8-3,031.4) were observed compared with healthy children (median, 232.2 pg/ml; range, 135.7-506.5) (p < 0.0038). Similar results were observed for INF-gamma concentrations (median, 121.1 pg/ml, and range, 5.3-228.8, in cases, and median, 89.6 pg/ml, and range, 10.9-117.2 in controls) (p < 0.0004). The diabetic carriers of the ff genotype showed low levels of 25(OH) vitamin D compared with the carriers of the F allele: mean (standard deviation), 23.1 (5.9) versus 27.9 (10.3) ng/ml (p < 0.03). A similar result was observed for TGF-beta1 concentrations in diabetic carriers of ff genotype and patients carriers of the F allele (298.5 versus 276.6; p < 0.05).


CONCLUSIONS
Fok I polymorphism of VDR could have a marginal role in the immunologic disturbance in type 1 diabetes.
López
Tatiana
T
Laboratorio de Epidemiología Nutricional y Genética, Instituto de Nutrición y Tecnología de los Alimentos (INTA), Universidad de Chile, Santiago, Chile.
García
Diego
D
Angel
Bárbara
B
Carrasco
Elena
E
Codner
Ethel
E
Ugarte
Francisca
F
Pérez-Bravo
Francisco
F
D000293:Adolescent; D016022:Case-Control Studies; D002648:Child; D002675:Child, Preschool; D003627:Data Interpretation, Statistical; D003922:Diabetes Mellitus, Type 1 / Q000235:genetics* / Q000276:immunology; D005787:Gene Frequency; D020022:Genetic Predisposition to Disease; D005838:Genotype; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007371:Interferon-gamma / Q000097:blood*; D011110:Polymorphism, Genetic; D012150:Polymorphism, Restriction Fragment Length; D018167:Receptors, Calcitriol / Q000235:genetics*; D053773:Transforming Growth Factor beta1 / Q000097:blood*
D018167:Receptors, Calcitriol; D053773:Transforming Growth Factor beta1; D007371:Interferon-gamma