Incidence of acetylcholine receptor‐antibody‐positive myasthenia gravis in South Africa

Abstract

In this Southern Hemisphere African population, the overall IR and peak IR (in older men) for seropositive MG is comparable to that in Europe and North America, arguing against environmental factors. However, IRs may be higher among children with African genetic ancestry. Geographical variation in incidence underscores the importance of outreach programs for regions with limited resources.

Myasthenic ophthalmoparesis: Time To resolution after initiating immune therapies

“…4 Another small, blinded randomized trial using prednisone found that 5 of 6 (83%) OM patients achieved resolution of their symptoms at a median of 14 weeks with a prednisone dose of 15 mg/day, although only half of the cases had severe visual QMG subscores, which would be comparable to the persistent ophthalmoparesis that we are studying, as opposed to fatigability. 5 Although the incidence of acetylcholine receptor antibody (AChR-ab)-positive MG in South Africa is similar to elsewhere, [6][7][8] we have reported a treatmentresistant ophthalmoplegic subphenotype of MG which, in our setting, appears almost uniquely in myasthenic patients with African-genetic ancestry. [9][10][11] Despite the current absence of a successful management plan for this MG subphenotype, our understanding of the pathogenesis is advancing, [12][13][14] and we are therefore interested in early identification of patients with MG with persistent ophthalmoplegia that shows treatment resistance.…”

“…Although the incidence of acetylcholine receptor antibody (AChR‐ab)‐positive MG in South Africa is similar to elsewhere, we have reported a treatment‐resistant ophthalmoplegic subphenotype of MG which, in our setting, appears almost uniquely in myasthenic patients with African‐genetic ancestry . Despite the current absence of a successful management plan for this MG subphenotype, our understanding of the pathogenesis is advancing, and we are therefore interested in early identification of patients with MG with persistent ophthalmoplegia that shows treatment resistance.…”

Characteristics Of acetylcholine‐receptor‐antibody–negative myasthenia gravis in a South African cohort

“…A report from North America suggested that MuSK‐MG may occur more frequently among African Americans compared with Americans with European genetic ancestry . We previously reported similar frequencies and age‐related incidence rates of AChR‐Ab–positive MG among different racial groups in South Africa that were comparable to the rest of the world . However, there are no data on MuSK‐MG or seronegative MG in African populations.…”

A unique subphenotype of myasthenia gravis

“…Although epidemiological studies from Africa are sparse, the incidence of acetylcholine receptor (AChR) antibody‐positive myasthenia gravis (MG) in South Africa appears similar to other populations, with an annual incidence of 8.5 per million . In addition, age‐standardized incidence rates show similar trends to those from developed countries and populations residing in the Northern hemisphere, including Asia, with late‐onset MG (≥50 years) approximately sixfold higher compared with early‐onset MG (<50 years) .…”

“…However, population genetic factors appear to influence the manifestation of MG in young children . Although few population studies have reported on childhood‐onset MG specifically, and study methodologies are not comparable, Chinese children have a higher incidence of MG than their Caucasian counterparts, perhaps more so than African children …”