Study of the association of β2-adrenergic receptor gene polymorphism with Myasthenia Gravis associated with thymus abnormality

Objective: To investigate the association of two β2-adrenergic receptor (β2-AR) polymorphisms (Arg16Gly, Gln27Glu) with Myasthenia Gravis (MG) associated with thymus abnormality.

Methods: Among the 74 MG patients in analysis, 24 cases were associated with thymoma, 40 cases with thymic hyperplasia, 12 with normal thymus. The genotypes of β2-AR in 76 MG (MGG) and 75 age and gender-matched healthy controls (HCG) were determined by polymerase chain reaction and nucleotide sequence determination.

Results: The frequencies of three genotypes (Arg/Arg, Arg/Gly, Gly/Gly) and alleles (Arg, Gly) in position 16 between MGG with thymoma and HCG (genotype χ(2) = 0.460, P = 0.895; allele χ(2) = 0.137, P = 0.711), MGG with thymic hyperplasia and HCG were not statistically insignificant (genotype χ(2) = 2.585, P = 0.278;allele χ(2) = 0.300, P = 0.584). The difference in distribution of the genotypes (Gln/Gln, Gln/Glu, Glu/Glu) and alleles (Gln, Glu) between MGG with thymoma and HCG (genotype P = 0.866; allele χ(2) = 0.030, P = 0.860), MGG with thymic hyperplasia and HCG (genotype P = 0.907; allele χ(2) = 0.373, P = 0.542) were statistically insignificant. The genotypes distribution of position 27 in different thymus histology (thymoma, thymic hyperplasia, normal thymus) of MGG were significantly different (P = 0.041). The genotype frequencies in all groups were both in Hardy-Weinberg equilibrium (P > 0.05).

Conclusions: Arg/Gly and Gln/Glu polymorphisms of β2-AR might have no relationship with the risk of MG associated with thymus abnormality. The genotypes polymorphism of position 27 may related with the different thymus histology of MG.