Whole Exome Sequence Analysis for Inborn Errors of IL-12/IFN-γ Axis in Patient with Recurrent Typhoid Fever

Association of single nucleotide polymorphism rs3213119 variant of IL-12B gene in diagnosed Rheumatoid Arthritis patients

Objective

To identify the IL12B gene variant (rs3213119) and to find its association in Pakistani clinical population of Rheumatoid Arthritis.

Methods

It was a population association (unrelated) case control study, performed from January - December 2022 at Laboratory of Department of Biochemistry and Molecular Biology, Army Medical College, Rawalpindi. Blood samples were collected from all 150 study participants, followed by DNA extraction and Allele-specific polymerase chain reaction performed at Center for Research in Experimental and Applied Medicine (CREAM) Laboratory of Department of Biochemistry and Molecular Biology, Army Medical College Rawalpindi. Statistical analysis was done using 'SPSS' (version-22), followed by gene analysis on 'SNPstat'.

Results

About 28.0% of RA patients were smokers, 38.7% had history of RA in a first degree relative and 70.7% had positive history of consanguinity. Considering rs3213119 variant of IL12B gene, frequency of major allele C was 100%, minor allele A was 21%, genotype C/C was 79% and C/A was 21%. Applying the log additive model, the odds ratio of the genotype C/C was 1.00 (adjusted by age and gender with 95 % CI) and the odds ratio of the genotype C/A was 0.00, 52.0% of RA patients originated from four predominant ethnic groups, namely Awaans (18.7%), Rajputs (14.7%), Pathans (12.0%) and Araeens (6.7%).

Conclusion

The study findings suggest the role of minor allele 'A' as risk allele in our clinical population. CA genotype confers susceptibility towards the RA development.

Consanguineous marriages increase the incidence of recurrent tuberculosis: Evidence from whole exome sequencing

BACKGROUND

In this study, we have identified multiple mutations in the IL-12R1 gene among Pakistani patients who have inherited them through consanguineous marriages. These patients have experienced severe Bacille-Calmette-Guérin (BCG) infection as well as recurrent tuberculosis. We will demonstrate the pivotal role of interleukin (IL)-12/interferon (IFN)-γ axis in the regulation of mycobacterial diseases.

METHODOLOGY

First, we checked the patients' medical records, and then afterward, we assessed interferon-gamma (IFN-γ) production through ELISA. Following that, DNA was extracted to investigate IL-12/IFN- abnormalities. Whole exome sequencing was conducted through Sanger sequencing. Secretory cytokine levels were compared from healthy control of the same age groups and they were found to be considerably less in the disease cohort. To evaluate the probable functional impact of these alterations, an in silico study was performed.

RESULTS

The study found that the patients' PBMCs produced considerably less IFN-γ than expected. Analysis using flow cytometry showed that activated T cells lacked surface expression of IL-12Rβ1. Exon 7 of the IL-12Rβ1 gene, which encodes a portion of the cytokine binding region (CBR), and exon 10, which encodes the fibronectin-type III (FNIII) domain, were found to have the mutations c.641 A > G; p.Q214R and c.1094 T > C; p.M365T, respectively. In silico analysis showed that these mutations likely to have a deleterious effect on protein function.

CONCLUSION

Our findings indicate the significant contribution of the IL-12/IFN-γ is in combating infections due to mycobacterium. Among Pakistani patients born to consanguineous marriages, the identified mutations in the IL-12Rβ-1 gene provide insights into the genetic basis of severe BCG infections and recurrent tuberculosis. The study highlights the potential utility of newborn screening in regions with mandatory BCG vaccination, enabling early detection and intervention for primary immunodeficiencies associated with mycobacterial infections. Moreover, the study suggests at the potential role of other related genes such as IL-23Rβ1, TYK2, or JAK2 in IFN-γ production, warranting further investigation.