Screening for antibodies against the Ri antigen is used to investigate patients with possible paraneoplastic syndrome.
Antibodies against the Ri antigen (also called Nova 1 or ANNA-2 antibodies or specific anti-neuronal nuclear antibodies 2), are rarer than antibodies against the Hu antigen but can occur in paraneoplastic sensory-cerebral ataxia or even in paraneoplastic encephalomyelitis. The presence of these antibodies is closely linked to small cell lung cancer. Neurological symptoms can precede the diagnosis of cancer up to five years earlier.
See also: Anti-Neuronal Antibodies