Introduction: Histamine N-methyltransferase (HNMT) is the main metabolizing enzyme of histamine. Histamine modulates immune responses and plays a role in the pathogenesis of autoimmune disorders. Methods: The non-synonymous HNMT C314T polymorphism and the A939G single-nucleotide polymorphism (SNP) influencing HNMT mRNA stability were genotyped in 213 patients with myasthenia gravis (MG) and 342 healthy controls. Results: The carrier frequency of the A allele of the A939G SNP was over-represented among patients with anti-AchR and anti-Titin antibodies (P= 0.05 and P= 0.004, respectively); the presence of the minor G allele was protective against anti-AchR and anti-Titin positive MG (OR = 0.67 and OR = 0.54, respectively). The combination of the G allele carrier status with wild-type C314C homozygosity was also protective against MG (OR = 0.55, P= 0.008) and against the development of anti-AchR antibodies (OR = 0.37, P= 0.01). Discussion: The A939G HNMT polymorphism is associated with autoimmune MG, while no association with C314T SNP was found.
ASJC Scopus subject areas
- Immunology and Allergy