# Comparative Analysis of COL9A1 Genotyping in Oral Squamous Cell Carcinoma Diagnosis: A Pilot Study
## 4 Discussion  
Over the past years, the incidence of OSCC has become a worldwide concern, and the importance of an early diagnosis, a proper staging, prognosis and further treatment requires an improvement in the current protocols. The incidence of this pathology is directly linked to exposure to environment mutagens that can determine genetic and epigenetic alterations of oral mucosa cells, with an increased risk for further malignant development [27 ]. Recently, more studies have focused on the epigenetic alterations of various genes that have potential as biomarkers and could improve early detection [27 ]. Numerous clinical applications of epigenetics have the potential to become new approaches for OSCC therapeutic strategies [27 ]. Blood sample analysis has the advantage of providing real-time information through specific oral cancer biomarkers regarding the tumour, tumour recurrence, metastasis, any evidence of drug resistance and the probability of developing OSCC through the presence of certain gene mutations [27 ]. Although an important number of genetic alterations has been associated with the incidence of OSCC in numerous studies [27 ], only several related mutations could be encountered among the population [27 ]. In addition, despite the fact that the P53 gene was strongly associated with OSCC, the results of a recent meta-analysis that focused on 2298 cases of diagnosed OSCC revealed the fact that it cannot be highly associated with the incidence of oral squamous cell carcinoma [27 ]. Figure 4: Blood samples’ genetic variants in correlation with clinical staging. Figure 3: Tissue samples’ genetic variants in correlation with clinical staging. Aiming to find a connection between the initiation and progress of the oral malignant process and gene variants, our attention was gained by a promising gene, COL9A1 through a tagged SNP [27 ]. Based on previous research and the Cancer Genome Atlas, the COL9A1 gene is responsible for the encoding of the three alpha chains of type IX collagen, and the targeted SNP (rs550675) in our study was highly associated with the occurrence of oral malignancy. Previous studies have reported that the methylation levels of COL9A1 decreased in association with OSCC incidence [27 ]. Different types of alterations in the gene's expression have been identified in the head and neck area, brain, heart, salivary glands, prostate and testis. Depending on the targeted SNP (single-nucleotide polymorphism), genetic mutations can be connected to different types of malignancies. This type of collagen is localised in multiple tissues, encoding one of the three alpha chains of collagen. The alpha 1 subunit of the gene is produced by non-cartilaginous tissues, such as skin, bone and arterial smooth muscles cells, and regulates the promoter of collagen type V [27 ]. Although collagen type IX is frequently associated with birth anomalies, its influence on adult life is not completely known. Studies have shown that the lack of the synthesis of the alpha 1 chain influences the assembly of collagen molecules and can be related with the onset of various diseases. It has been reported that mutations in this gene can be associated with ophthalmic, orofacial disorders and articular and auditory defects [27 ]. Existent results have shown that modification of the methylation in the COL9A1 gene can be identified in breast cancer, and in their study, [PERSON] et al. [27 ] encountered a general drop in methylation of COL9A1 in the CpG island of tumour breast samples. [PERSON] et al. [27 ] analysed the involvement of COL9A1 through miR-9-3 in liver hepatocellular carcinoma. Their results showed that COL9A1 was enriched in focal adhesions, suggesting an important role in the carcinogenesis of liver. High levels of COL9A1 were reported as well in fibroblasts associated with lung cancer patients [27 ] and colorectal cancer [27 ]. In the case of head and neck cancer, [PERSON] et al. [27 ] reported that COL9A1 was present in the tumour tissue and undetectable in the corresponding normal tissue.