Association with HLA DQ of early onset myasthenia gravis in Southeast Texas region of the United States.

Forty-four Caucasian American myasthenia gravis (MG) patients from Southeast Texas underwent high resolution HLA DQ analysis. For the majority of patients who were late onset or male, no significant associations with DQ were observed. However, associations with DQ increased in female patients and early onset patients. At the allele level, DQB1 *0503, *0604, *0502 and *0402 collectively contributed to a positive association of the DQ locus with early onset MG (EOMG), while individually failing to show significant association. At DQ level, the novel haplotype DQA1*0401:DQB1*0201 was the primary factor in the association of combined DQ loci with early onset. In addition, *0104:*0503, *0102:*0604, *0102:*0502 and *0303:*0402 collectively contributed to the positive association of the haplotype loci. DR3-DQ2.5cis, a well known risk factor for MG in Western Eurasia, was not found associated with disease in any group. For typical EOMG [early onset, no thymoma, anti-acetylcholine receptor (AChR) antibody (Ab) positive] no association with DQA1 locus was found, however DQB1*0604 demonstrated an 'uncorrected' positive association. A few DQ haplotype (DQA1:DQB1) were positively associated with typical EOMG; a positive individual association for *0401:*0201 was complimented by the contributions of *0102:*0604 and *0303:*0402 haplotypes. A small minority of patients that were atypical and EOMG had a strong genetic association with DQA1*0104:DQB1*0503, the group included an anti-MuSK Ab positive and an anti-AChR negative patient. This report finds common ground with European studies regarding MuSK association; however similarities in association for typical early onset disease resembled HLA risk factors in East Asia and Southern Europe.
(© 2010 Blackwell Publishing Ltd.)