J Korean Diabetes Assoc.
1998 Jun;22(2):155-163.
NcoI Restriction Fragment Length Polymorphism(RFLP) on the TNF-beta gene in Korean Patients with
Type 1(insulin-dependent) Diabetes Mellitus
Abstract
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BACKGROUND: To investigate whether a TNF-g gene polymorphism is associated with the development of
insulin-dependent diabetes mellitus, we analyzed the TNF-g gene polymorphism with restriction enzyme
Ncol in 38 Korean patients with insulin -dependent diabetes mellitus(IDDM) and in 150 healthy controls.
METHODS
Genomic DNA was extracted from white blood cells, and amplified by polymerase chain
reaction(PCR) on 735 base pairs fragment of TNF-g gene with NcoI polymorpnic site. 735 bp PCR
product was digested with NcoI restriction endonuclease, then analyzed by agarose gel electrophoresis
to detect the NcoI restriction fragment length polymorphism(RFLP). The TNF-g alleles were divided into two
types according to the electrophoresis patterns. TNF-b*1 allele, which contains the Ncol restriction site(CCATGG),
should be digested 539 bp and 196 bp fragments. On the other hand, TNF-g*2 allele, which lacks the restriction site,
only showed 735 bp fragment. RESULTS: Six out of 38(15.8%) IDDM patients were homozygous for the TNF-b*1 allele,
11(28.9%) were homozygous for the TNF-b*2 alleie, and 21 (55.3%) were TNF-b*1/*2 heterozygous compared to
21.7%, 30.7% and 49.3%(p=0.83), respectively, in control subjects. CONCLUSION: The TNF-b gene polymorphism was
not associated with insulin-dependent diabetes mellitus in Korean subjects.