Interaction of vitamin D receptor with HLA DRB1 0301 in type 1 diabetes patients from North India.
BACKGROUND
Type 1 diabetes (T1D) is a multifactorial autoimmune disorder where interaction and integration of immune response genes along with environmental factors play a role in autoimmune destruction of the insulin producing Pancreatic Beta cells.


RESULTS
We have studied four single nucleotide polymorphisms (FokI site in Exon 2, BsmI and ApaI sites in Intron 8 and TaqI site in exon 9) in the vitamin D receptor (VDR) gene using PCR-RFLP and HLA-DRB1 alleles using PCR and hybridization with sequence specific oligonucleotide probes and studied their interaction using LD based statistics for non-linked loci followed by sequence analysis of the vitamin D response element (VDRE) present in the promoter region of HLA-DRB1 0301. Haplotypes, constructed using SHEsis program for four single nucleotide polymorphisms in the VDR gene, were studied for their interaction with HLA-DRB1 alleles in 233 T1D patients and 191 healthy controls from North India. A significant increase of haplotypes FBAt and fBAT (p<0.02, OR = 1.44 and p<0.002, OR = 3.23 respectively) was observed in the patients. Both the haplotypes FBAt and fBAT were significantly increased in male patients with age at onset less than 18 years; however, fBAT was significantly increased in female patients irrespective of their age at onset. LD based statistics showed significant interaction between the high producer F and T alleles with HLA-DRB1 0301. F and T alleles of VDR have been shown to contribute to VDR mRNA independently. The promoter sequence analysis of HLA-DRB1 0301 showed presence of VDRE involved in higher expression of HLA-DRB1 030, which was confirmed by flow cytometry and real time PCR analysis.


CONCLUSIONS
These data suggest that the interaction between VDR and HLA alleles is mediated by VDRE present in the promoter region of HLA-DRB1 0301 allele, which may be detrimental for the manifestation of T1D in the absence of 1,25-(OH)(2)D(3) in early childhood due to poor expression of DRB1 0301 in the thymus resulting in autoimmunity.
Israni
Neetu
N
Molecular Immunogenetics Group, National Institute of Immunology, New Delhi, India.
Goswami
Ravinder
R
Kumar
Avinash
A
Rani
Rajni
R
D017668:Age of Onset; D000483:Alleles; D001483:Base Sequence; D002117:Calcitriol / Q000494:pharmacology; D016022:Case-Control Studies; D003922:Diabetes Mellitus, Type 1 / Q000453:epidemiology / Q000235:genetics*; D005260:Female; D005434:Flow Cytometry; D005786:Gene Expression Regulation / Q000187:drug effects; D020022:Genetic Predisposition to Disease; D006684:HLA-DR Antigens / Q000235:genetics*; D059811:HLA-DRB1 Chains; D006239:Haplotypes / Q000235:genetics; D006801:Humans; D007194:India / Q000453:epidemiology; D008297:Male; D008969:Molecular Sequence Data; D020641:Polymorphism, Single Nucleotide / Q000235:genetics; D011401:Promoter Regions, Genetic / Q000235:genetics; D018167:Receptors, Calcitriol / Q000235:genetics*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017422:Sequence Analysis, DNA; D012727:Sex Characteristics
D006684:HLA-DR Antigens; D059811:HLA-DRB1 Chains; C553502:HLA-DRB1*03:01 antigen; D018167:Receptors, Calcitriol; D002117:Calcitriol