Macular telangiectasia type 2 (MacTel) is a rare degenerative retinal disease characterized by changes in retinal morphology and its' microenvironment. Initial research described MacTel as a vascular disease. With improved imaging techniques that allow better visualization of retinal structure and function, this view has shifted. It is now understood that MacTel is primarily a neurodegenerative disorder, with vascular changes such as telangiectasia and neovascularization arising as secondary effects. The exact cause of the disease remains unknown, but since it occurs in multiple family members and twins, it is assumed to have a genetic background. The aim of this work was to analyze genetic variants already associated with the disease to determine their frequency and significance for the onset of MacTel in a selected cohort of Slovenian patients. In the first part of research, we conducted a detailed analysis of the molecular-genetic background of MacTel by reviewing existing literature and databases, focusing on the metabolic pathways involving these genes and their interactions. We evaluated the relevance of previously identified variants in the PHGDH, CPS1, CERS4, MIR9-2HG, SLC20A6, REEP3, and SPTLC1 genes in the context of MacTel pathogenesis. The theoretical overview confirmed the involvement of selected variants in amino acid and lipid metabolic pathways and a potential link between the variant and protein function or structure for five of the seven variants. In the second part of the study, we experimentally assessed the presence of selected gene variants in a cohort of Slovenian patients using TaqMan probes. We analyzed the presence of seven selected variants in 67 patients diagnosed with MacTel and eight family members and examined the co-occurrence of each selected variant. The genotyping results were statistically evaluated and compared with previous findings. We have determined that the selected variants, which are either protective (less frequent in patients) or pathogenic (more frequent in patients), also occur in Slovenian patients. The results of this research contributed to a better understanding of the prevalence of selected genetic variants in Slovenian patients diagnosed with MacTel and highlighted the crucial role of in-depth understanding of associated metabolic pathways in developing targeted molecular-genetic diagnostics for this complex degenerative retinal disease.
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