# IFN-γ +874 T/A Is Associated with High Levels of Sera CPK in Patients with Inflammatory Myopathies

## TL;DR

This study explores how a genetic variant in IFN-γ is linked to higher muscle damage markers in patients with inflammatory myopathies.

## Contribution

The study identifies a potential genetic link between IFN-γ polymorphism and elevated CPK levels in inflammatory myopathy patients.

## Key findings

- The TT genotype of IFN-γ +874 T/A is associated with higher CPK levels in inflammatory myopathy patients.
- No overall association was found between IFN-γ +874 T/A polymorphism and disease development in IIM patients.
- Higher CPK levels were observed in females at diagnosis and males in remission with the TT genotype.

## Abstract

Aim of the study: Idiopathic inflammatory myopathies (IIM) are autoimmune diseases with a low prevalence and incidence worldwide. The levels of IFN-γ production by T-lymphocytes are related to disease activity. IFN-γ +874 T/A (rs2430561) has been shown to alter the serum levels of IFN-γ in different pathologies. The aim of this work is to explore the role of IFN-γ +874 T/A polymorphism in IIM. Methods: Using a specific sequence primer-polymerase chain reaction (SSP-PCR), the genotype was defined for normal healthy controls (HC) and patients with IIM. Markers of muscle damage, clinical features and treatment were collected from chart at the time of diagnosis and at recruitment point. All the data were analyzed by demographic characteristics, genotype, type of IIM, treatment, clinical features, and enzymatic levels. Results: No association was found comparing the genotypes or alleles of the IIM patients vs. HC. On the other hand, the TT genotype, previously described as a high producer of INF γ, showed higher levels of CPK at diagnosis in IIM patients, whereas females at diagnosis and males in remission presented higher levels. Conclusions: Even with a limited number of patients due to the rarity of this disease, no association was found between the disease development. Further, the TT genotype promoted muscle damage due to CPK elevation in the sera compared to the TA/AA genotype in patients with IIM. This could be genetic evidence of the impact of IFN-γ in the disease activity of IIM patients. A larger cohort is needed to confirm these results.