Patients with myasthenia gravis (MG) who are positive for a combination of both anti-acetylcholine receptor (AChR) and anti-Titin antibodies (AChR+Titin-MG) had more severe symptoms and progressed faster than patients with only anti-AChR (AChR-MG), and those with anti-AChR in combination with anti-low-density lipoprotein receptor-related protein 4 (LRP4) antibodies (AChR+LRP-MG), as published in Frontiers in Neurology.

Patients with MG with AChR+Titin-MG showed shorter conversion times from the onset of ocular muscle weakness symptoms to generalized MG symptoms compared to patients with AChR-MG and AChR+LRP-MG (5.14 months vs 11.69 months and 13.08 months, respectively; P <.001).

The AChR+Titin-MG group also had greater bulbar dysfunction than the other 2 groups and had a higher incidence of thymoma (32.8% vs 19.8% for AChR-MG and 3.4% for AChR+LRP-MG; P =.006).

Disease severity measures including quantitative MG (QMG) scores and the Myasthenia Gravis Activities of Daily Living scale (MG-ADL) were worse in the AChR+Titin-MG group. Patients with AChR+Titin-MG had mean QMG scores of 15.5 compared to 13 in the AChR-MG group (P =.005) and 9 in the AChR+LRP-MG group (P <.001). MG-ADL scores were also higher in the AChR+Titin-MG group with a mean value of 10 compared to 8 in the AChR-MG group (P =.018) and 6 in the AChR+LRP-MG group (P <.001).

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MGFA classifications also tended to be worse in the AChR+Titin-MG group with 48.2% of patients being classified as MGFA IVb-V compared to 33.2% in the AChR-MG group and 24.1% in the AChR+LRP-MG group (P =.02). The AChR+LRP-MG group had a more benign classification with almost half (48.3%) of patients having the less severe MGFA IIa classification.

All patients received standard therapies for MG including pyridostigmine. The percentages of patients who received Minimal Manifestation Status or better within 2 years after immunosuppressive treatment were 51.5% for AChR-MG, and 62.1% for AChR+LRP-MG, and 51.7% for AChR+Titin-MG.

“Clinical symptoms of anti-AChR positive MG combined with Titin antibody were more severe and progressed faster than those in the AChR + LRP4 and AChR groups. Regardless of antibody status, all patients responded well to immunotherapy and had relatively good prognose,” the authors concluded.

A total of 188 patients seropositive for anti-AChR antibodies were enrolled in the study with 29 patients also positive for anti-LRP4 antibodies, and 58 patients also had anti-Titin antibodies. The ages at onset between the 3 groups were not significantly different but the AChR+LRP-MG group had a predominance of female patients (72.4%). The gender proportions in the other 2 groups were relatively equal and not significantly different between groups.

Reference

Chen Y, Tao X, Wang Y, et al. Clinical characteristics and prognosis of anti-AChR positive myasthenia gravis combined with anti-LRP4 or anti-Titin antibody. Front Neurol. 2022;13. doi:10.3389/fneur.2022.873599