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Opsoclonus-myoclonus syndrome. Not all patients present opsoclonus but the majority develop other symptoms of brainstem involvement characterized by supranuclear gaze palsies, parkinsonism, rigidity, dizziness, dysarthria, and dysphagia.
Breast cancer or small-cell lung cancer (SCLC).
Frequency of anti-Ri antibodies in patients with suspected paraneoplastic neurological syndromes (PNS) without evidence of cancer: 3%
Frequency of anti-Ri antibodies in patients with cancer without PNS:
4% in a series of 161 patients with ovarian cancer. Frequency in breast
cancer or SCLC is unknown.
Immunohistochemistry on frozen brain sections (human, monkey, rabbit, rat, mouse) (figure 1).
Figure 1. Anti-Ri immunoreactivity
is identical to that of anti-Hu on neurons of the central nervous
system but, unlike anti-Hu, anti-Ri antibodies do not immunoreact
with neurons of the peripheral nervous sytem. Immunostaining of
a rat section showing the spinal cord (SC) and spinal ganglia
(SG). |
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Several commercial tests using immunoblots of recombinant NOVA protein. Immunoblot of neurons identifies a set of antigens of 53 to 61 Kd and 79-84 Kd (figure 2)
Figure 2. Immunoblot of neuronal nuclei homogenate probed with serum (1) and CSF (2) of a patient with anti-Ri antibodies. Lane 3, anti-Hu positive serum.
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Patients with paraneoplastic syndromes, anti-Ri antibodies and SCLC may also harbor anti-Hu antibodies.
The target of anti-Ri antibodies is a family RNA-binding proteins that are mainly expressed in the nervous system. The two Ri antigens are Nova-1 and Nova-2. The Nova proteins contain three RNA-binding domains called KH (for K homology). The Nova proteins are critical for the development and maintenance of the neuronal phenotype in mammals. Postnatal Nova-1-null mice present an increase in apoptosis in hindbrain and ventral spinal cord neurons.
1. Drlicek M, Bianchi G, Bogliun G, et al. Antibodies of the anti-Yo and anti-Ri type in the absence of paraneoplastic neurological syndromes: a long-term survey of ovarian cancer patients. J neurol 1997;244:85-9.
2. Luque FA, Furneaux HM, Ferziger R, et al. Anti-Ri: an antibody associated with paraneoplastic opsoclonus and breast cancer. Ann Neurol 1991;29:241-51.
3. Musunuru K, Darnell RB. Paraneoplastic neurological
disease antigens:RNA-binding proteins and signaling proteins in neuronal
degeneration. Annu Rev Neurosci 2001;24:239-62.
4. Pittock SJ, Lucchinetti CF, Lennon VA. Anti-neuronal nuclear autoantibody
type-2: Paraneoplastic accompaniments. Ann Neurol 2003;53:580-7.
5. Sutton IJ, Barnett MH, Watson JDG, et al. Paraneoplastic brainstem
encephalitis and anti-Ri antibodies. J Neurol 2002;249:1597-8.
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Updated 2009-09-15
