RT Journal Article SR Electronic T1 Anti-amphiphysin I antibodies in patients with paraneoplastic neurological disorders associated with small cell lung carcinoma JF Journal of Neurology, Neurosurgery & Psychiatry JO J Neurol Neurosurg Psychiatry FD BMJ Publishing Group Ltd SP 214 OP 217 DO 10.1136/jnnp.66.2.214 VO 66 IS 2 A1 Saiz, A A1 Dalmau, J A1 Butler, M Husta A1 Chen, Q A1 Delattre, J Y A1 De Camilli, P A1 Graus, F YR 1999 UL http://jnnp.bmj.com/content/66/2/214.abstract AB Patients with stiff man syndrome and breast cancer develop anti-amphiphysin I antibodies that primarily recognise the C terminus of the protein. Anti-amphiphysin I antibodies have also been identified in a few patients with paraneoplastic neurological disorders (PND) and small cell lung cancer (SCLC). The frequency of anti-amphiphysin I antibodies in patients with SCLC and PND was analysed and the epitope specificity of these antibodies was characterised.  Anti-amphiphysin I antibodies were evaluated by immunohistochemistry on human and rat cerebellum and immunoblots of rat brain homogenates. Serum samples included 134 patients with PND and anti-Hu antibodies (83% had SCLC), 44 with SCLC and PND without antiHu-antibodies, 63 with PND and either Yo, Ri, or Tr antibodies, 146 with SCLC without PND, and 104 with non-PND. Positive serum samples were confirmed with immunoblots of recombinant human amphiphysin I and immunoreacted with five overlapping peptide fragments covering the full length of the molecule.  Serum samples positive for anti-amphiphysin I antibodies included those from seven (2.9%) patients with PND and two (1.4%) with SCLC without PND. Six of the seven anti-amphiphysin I antibody positive patients with PND had SCLC (three with Hu-antibodies), and one had anti-Hu-antibodies but no detectable tumour. The PND included encephalomyelitis/sensory neuropathy (five patients), cerebellar degeneration (one), and opsoclonus (one). All anti-amphiphysin I antibodies reacted with the C terminus of amphiphysin I, but seven also recognised other fragments of the molecule.  In conclusion, anti-amphiphysin I antibodies are present at low frequency in patients with SCLC irrespective of the presence of an associated PND. All anti-amphiphysin I antibody positive serum samples have in common reactivity with the C terminus of the protein.