CTLA4 gene polymorphisms and multiple sclerosis in Northern Ireland

Area of Science:

• Genetics
• Immunology
• Neurology

Background:

• Multiple Sclerosis (MS) is a chronic autoimmune disease affecting the central nervous system.
• Genetic factors, including polymorphisms in the Cytotoxic T-Lymphocyte Associated protein 4 (CTLA4) gene, are implicated in MS susceptibility and progression.
• Understanding these genetic associations can provide insights into disease mechanisms and potential therapeutic targets.

Purpose of the Study:

• To investigate the association of four specific CTLA4 polymorphisms with relapsing-remitting MS (RRMS) and primary-progressive MS (PPMS) in a Northern Irish cohort.
• To determine if CTLA4 gene variants influence the clinical course or susceptibility to different forms of MS.
• To identify potential genetic markers for MS subtypes.

Main Methods:

• Genotyping of four CTLA4 polymorphisms: promoter (-318 C/T), exon 1 (+49 A/G) SNP, CT60 SNP, and a 3' UTR microsatellite (AT(n)).
• Analysis was performed on DNA samples from 246 RRMS patients, 84 PPMS patients, and 158 healthy controls.
• Statistical analysis, including odds ratios and confidence intervals, was used to assess associations between genotypes/alleles and MS subtypes.

Main Results:

• The A allele and AA genotype of the CTLA4 exon 1 +49 A/G SNP were significantly associated with RRMS (OR=1.36, P=0.038; OR=1.70, P=0.015, respectively).
• No significant association was found for the promoter (-318 C/T) or CT60 SNPs in either MS cohort.
• The AT(n) microsatellite in the 3' UTR showed a significant difference in allele distribution in PPMS patients compared to healthy controls.
• A trend for higher carriage of the +49 G allele in PPMS versus RRMS patients was observed but did not reach statistical significance.

Conclusions:

• The CTLA4 exon 1 +49 A/G polymorphism, particularly the A allele and AA genotype, may be a genetic modifier associated with susceptibility to RRMS.
• The CTLA4 3' UTR AT(n) microsatellite might also play a role in the pathogenesis or disease course of PPMS.
• These findings highlight specific CTLA4 polymorphisms as potential contributors to the heterogeneity of multiple sclerosis.
• Further research is warranted to elucidate the functional impact of these CTLA4 variants in MS.