Abstract
A 10-year-old girl presented with ileus, urinary retention, dry mouth, lack of tears, fixed dilated pupils, and diffuse anhidrosis 7 days after a febrile illness. We hypothesized that her syndrome was due to autoimmunity against muscarinic acetylcholine receptors, blocking their activation. Using an indirect enzyme-linked immunosorbent assay for all 5 muscarinic receptors (M(1) -M(5) ), we identified in the patient's serum antibodies that selectively bound to M(3) receptors. In vitro functional studies confirmed that these autoantibodies selectively blocked M(3) receptor activation. Thus, autoantibodies against M(3) acetylcholine receptors cause acute postganglionic cholinergic dysautonomia. ANN NEUROL 2020;88:1237-1243.