HLA antigens and acetylcholine receptor antibody in the subclassification of myasthenia gravis in Hong Kong Chinese.

Abstract

Thirty seven Chinese adults and 23 children in Hong Kong with myasthenia gravis were tested for HLA-A and-B antigens and acetylcholine receptor (AChR) antibody. HLA BW46 had a significantly increased prevalence in patients with juvenile onset ocular myasthenia gravis. Only one third of the juvenile ocular patients had AChR antibodies and the titres were generally low. In the adult patients taken as a whole there was a non-significant increase in the prevalence of HLA B5 and HLA B 15. HLA BW46 was more prevalent in adult patients without AChR antibody and less prevalent in patients with AChR antibody but the findings were not statistically significant. It is suggested that ocular myasthenia gravis is determined by a pathological mechanism for which susceptibility is determined by HLA BW46. There was a strong correlation between ocular myasthenia gravis and Graves' disease in the adult patients. The possibility that ocular myasthenia gravis is accentuated by a BW46-associated predisposition to ocular Graves' disease is considered. Myasthenia gravis is a heterogeneous disease. Some patients have involvement of the extra-ocular muscles only and are considered to have "ocular myasthenia gravis" whereas others have disease extending beyond the extra-ocular muscles and are classified as having "generalised myasthenia gravis".1 The discovery2 of antibodies to the acetylcholine receptor (AChR) in the serum of most patients with generalised myasthenia gravis but less frequently in patients with ocular disease led to the question whether generalised myasthenia gravis and ocular myasthenia gravis represent different diseases or whether ocular myasthenia gravis is a less severe form of the generalised disease.3 The accumulated evidence appears to favour the suggestion that ocular and generalised myasthenia gravis represent different disorders.4 It is now well established, for example, that HLA B8 in Caucasian patients occurs frequently in females with generalised

Strong association between HLA DRw9 and Hashimoto's thyroiditis in Southern Chinese

“…This linkage disequilibrium may explain the finding of an increased frequency of HLA Bw46 prior to statistical adjustment, both in the patients in this study and in the study by Yeo et al (1983). Also in Southern Chinese, HLA Bw46 and DRw9 are known to be associated with other autoimmune diseases including Graves' disease, myasthenia gravis, and insulin dependent diabetes mellitus (Hawkins et al , 1986. In Caucasians these diseases are associated with HLA B8 and HLA DR3 which are themselves in strong linkage dise¬ quilibrium.…”

An approach to the localization of the susceptibility genes for generalized myasthenia gravis by mapping recombinant ancestral haplotypes

“…These data suggest that this segment of the MHC is found in patients with GMG because it carries susceptibility genes marked by and close to HLA B. In the Asian Indians and the Japanese the same genes may be carried by other haplotypes; the same may be true of the Chinese although the association with DR9 may reflect clinical heterogeneity (Hawkins et al 1986). …”

Anti-Acetylcholine Receptor Antibody in Myasthenia Gravis

“…In this respect Vincent and Newsom-Davis [33] reported that many of the ocular or generalized myasthenic sera with low antibody titers reacted better with human ocular or normal human muscle AChR than with denervated human muscle AChR. In regard to HLA antigen versus disease heterogeneity, the study on Hong Kong Chinese myasthenics [34] indicated that those with HLA Bw46 had a noticeably elevated prevalence of juvenile-onset ocular MG. In Japan, HLA and Gm have been defined as genetic markers in this disease, but there is no evidence which suggests the association of a specific HLA or Gm with myasthenia of ocular form or generalized form with negative titer of anti-AChR antibody.…”