Transforming growth factor-β-1 polymorphisms are infrequent but exist at selected loci in oral submucous fibrosis.

Background : Oral submucous fibrosis (OSF) may be considered a collagen metabolic disorder resulting from areca-nut alkaloid exposure and individual variation in collagen metabolism. Due to the complexity of OSF pathogenesis, it is important to elucidate independent and interactive effects of polymorphisms of collagen-related genes on OSF risk. Materials and Methods : This study is focused on seven polymorphisms (SNPs) of transforming growth factor-beta-1 (TGF-beta-1) gene in patients with oral submucous fibrosis (OSF), belonging to south Indian ethnic extraction. The mean age at presentation was 43.9 years, range 23-72 years (n=50, M:F ratio, 2.6:1). DNA samples from 50 subjects of the same ethnic group and comparable demographic features who have had practiced the habit of areca-chewing of almost equal duration, but remained free of disease constituted the controls. All DNA samples were collected progressively and purified from peripheral blood employing standard protocols and tested for SNPs. They included two polymorphisms in the promoter region (C-509T and G-800A), three polymorphisms in exon-1 (Arg25Pro(G915C), Leu10Pro(T869C), Glu47Gly(A979G) and two in 5 ͲUTR regions (C→T(rs13306708) and G→A (rs9282871). The extracted DNA samples along with the primers underwent PCR amplification and the genotypic and allelic frequencies were calculated. All calculations were performed using the SPSS software. The PCR products were purified and subsequently sequenced using Flour S™ multi-imager system (Biorad). The sequenced data were analyzed using the BioEdit sequence analysis software. Results : Out of the seven polymorphisms analyzed, six such as two in the promoter region, three in exon-1 and one in 5¢UTR were found to have a " P" value above 0.05 and hence were not significant. The C→T transition (rs13306708) in the 5¢UTR region recorded a " P" value of 0.03 on comparison and hence was found to be significant. The allelic frequencies for this C→T transition in patients were 68.7% C and 31.2% T (27CC, 15CT, 8TT) and that in controls were 89.5% C and 10.4% T (42CC, 6CT, 2TT). Conclusions : The polymorphism in 5¢UTR C-T in TGF beta 1 gene has a significant association with OSF, being a prime determinant in the pro-angiogenic pathway which has got direct bearing with the pathophysiology of the disease. The proximity of this polymorphism to the transcription site and the associated risk involved is discussed.

Immunological studies in oral submucous fibrosis.

Oral submucous fibrosis (OSMF) is a high risk precancerous condition. The possible role of immunological factors in the pathogenesis of this condition was evaluated in 113 cases and 25 controls. The male/female ratio was 1.5/1. The mean age of males was significantly lower than that of females. The mean ESR levels were within normal limits, but for a higher than 20 mm fall per hr. in 40% of the cases. The serum IgA, IgG, and IgM levels were elevated significantly as compared to the controls. Circulating auto-antibodies and tissue-deposited antibodies were also found in 33% and 40% of the cases, respectively. From the analysis of the results, it is difficult to ascribe an auto-immune basis for the causation of OSMF. The female bias and elder age group, the factors generally considered in favour of an immune disorder, was not found in our study. However, raised ESR in 40% and serum globulin levels in 47% of the patients, distinctly higher levels of serum immunoglobulins, and positivity for circulating and tissue deposited antibodies in 33% and 34% of the cases respectively, do indicate an immunological basis. Therefore, further studies are required to ascertain the role of cellular immune mechanism and genetic parameters to explain the etiopathogenesis of this complex clinical entity.