Development in medical technology has paved a way towards diagnosing and prevention of many diseases. Systemic lupus erythematosus (SLE) is one of them in which tolerance is lost against antigens and immune system of the body attacks healthy tissues of the body resulting in formation of immune complexes1,2. SLE is characterized by chronic inflammation of several organs including; central nervous system and kidney and lungs as well as clinical menifestations including chronic, acute and subacute-cutaneous lupus erythematosus, photosensitivity3,4.
Multiple chromosomal regions including complement genes are strongly associated to SLE and are highly susceptible 5,6. Complement lacking in the classical pathway, especially C1q, is found to be most powerful risk factors for SLEonset7. C1q (a multifunctional protein) is a fundamental component of the classical pathway and both complement and non-complement functions are outcomes of C1q. Moreover, C1q can affect toll-like receptor-mediated cytokine production and immune complex-induced IFN-α production, providing further explanations for the increased SLE risk associated with inherited deficiencies of C1q8. It is calculated that the frequency of SLE disease is 95% for all patients with C1q deficiency9.
The human genome exhibits several genetic variations ranging including microscopically visible chromosome abnormalities and single nucleotide polymorphisms (SNPs)10. According to some researches, SNPs play a vital role in tracking the inheritance of disease genes within families e.g. type 2 diabetes, sickle cell anemia, cancers, autoimmune diseases etc.11. Some genetic investigations revealed that single synonymous SNP in the C1Q gene regions are interlinked with SLE susceptibility12. Correspondingly; an experiment was performed to confirm the occurrence of SNPs in C1Q A-, B-, C-gene coding regions and their link with SLE.
Results detected the presence of three silent SNPs were detected, one each in the coding regions of C1QA, B and C genes in the SLE patients and control group of Caucasians groups and African Americans. These three SNPs, designated as C1QA276G>A, C1QB66C>A and C1QC129G>A are identical, having no impact on the protein sequence of C1q A-, B- and C-polypeptides.
No major differences were noted in the distribution of the genotype or allele frequencies between patients and controls for the C1qA chain or C1qB chain SNP. On the other hand, the C1qC chain SNP, particularly the 129GG genotype, was linked with defense against SLE but only in the Caucasian cohort. Thorough investigation should be done to verify this connection and mechanism of this relationship in separate normal and SLE Caucasian cohorts.
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17 November, 2019