Sydenham's Chorea: Is There a Link Between Neuropsychiatric Symptoms and Anti-dopamine Receptor Autoantibodies?

Sydenham's chorea (SC) is a post-streptococcal, neuropsychiatric disorder associated with anti-neuronal antibodies. The investigators demonstrated elevated anti-D1-receptor (D1R) and anti-D2-receptor (D2R) antibodies titers compared to controls using ELISA. Similarly, the investigators found antibodies to surface D2R in neuropsychiatric, autoimmune disorders, including SC using cell-based assays. The investigators hypothesize that these autoantibodies cause neuropsychiatric symptoms by inducing intracellular signaling changes resulting in altered dopaminergic neurotransmission. To check this, the investigators will test whether sera from patients with SC alter dopaminergic signaling pathways. The investigators will examine sera from 30 SC patients with active symptoms and 30 age-matched healthy controls. Patients with SC will be assessed for severity of neuropsychiatric symptoms using UFMG Sydenham's Chorea Rating Scale. Controls with evidence of streptococcal infections or autoimmune disorders will be excluded. Sera will be examined for anti-D1R and anti-D2R antibodies. Signaling studies will assess sera impact on 1) calcium/calmodulin-dependent protein kinase II activity in human neuronal cells. 2) dopamine D1/D2 receptors signaling using cAMP assays in transfected cell lines. The investigators will examine the correlation between modified signaling and clinical symptoms.