Role of β2-adrenergic receptor polymorphisms in prognosis of myasthenia gravis with other autoimmune diseases

Abstract

Objective To explore the correlation of β2-adrenergic receptor (β2-AR) polymorphisms (Arg16Gly) with the prognosis of myasthenia gravis (MG) complicated with other autoimmune diseases. Methods Among the 75 MG patients in analysis, 17 cases were complicated with other autoimmune diseases (AIDMG), 58 cases without other autoimmune diseases (NAIDMG). MG patients, AIDMG patients, NAIDMG patients were separately divided into recurrence groups and non-recurrence groups according to the progression at 2 years after onset. The genotypes of β2-AR in 75 MG patients were determined by gene sequecing. Results The frequencies of three genotypes (Arg/Arg, Arg/Gly and Gly/Gly) in position 16 were 30.8%, 50.0%, 19.2% in recurrence MG group and 42.9%, 38.8%, 18.3% in non-recurrence MG group respectively. The difference in distribution of the genotypes between recurrence MG group and non-recurrence MG group was not statistically significant (χ2=1.150, P=0.563). The frequencies of Arg and Gly allele were 55.8% and 44.2% in recurrence MG group, and 62.2% and 37.8% in non-recurrence MG group. The difference in distribution of the alleles between the two groups was not statistically significant. The frequencies of 3 genotypes in position 16 were 27.3%, 63.6% and 9.1% in recurrence AIDMG group and 100.0%, 0, 0 in non-recurrence AIDMG group, respectively. The frequencies of Arg and Gly allele were 59.1%, 40.9% in recurrence AIDMG group, and 100.0%, 0 in non-recurrence AIDMG group. The difference in distribution of the genotypes between recurrence AIDMG group and non-recurrence AIDMG group was statistically significant (P=0.009). There also was significant difference in distribution of alleles between recurrence and non-recurrence AIDMG groups (χ2=6.676, P=0.010). The frequencies of 3 genotypes in position 16 were 33.3%, 40.0% and 26.7% in recurrence NAIDMG group and 34.9%, 44.2%, 20.9% in non-recurrence NAIDMG group, respectively. The frequencies of Arg and Gly allele were 53.3%, 46.7% in recurrence NAIDMG group, and 57.0%, 43.0% in non-recurrence NAIDMG group. There was no significant difference in distribution of genotypes or alleles between recurrence and non-recurrence NAIDMG groups. Conclusion β2-AR gene polymorphism in position 16 may predict the prognosis of AIDMG, and there is no correlation between the polymorphism in position 16 of β2-AR and the prognosis of MG and NAIDMG. Key words: Myasthenia gravis; Receptors, adrenergic, beta-2; Polymorphism, genetic; Autoimmune diseases; Prognosis