In patients with cancer, symptoms of limbic and brainstem dysfunction may result from a paraneoplastic disorder. Paraneoplastic limbic or brainstem encephalitis occurs more frequently with testicular cancer than with most other cancers.
By immunohistochemical and immunoblotting techniques, Voltz et al. (1999) detected antibodies in serum and cerebrospinal fluid against a 40-kD neuronal protein in 10 of 13 patients with testicular cancer and paraneoplastic limbic or brainstem encephalitis, or both. They designated the protein MA2, and found that it was selectively expressed by normal brain tissue and by the testicular tumors of the patients. MA2 shares homology with MA1, a 'brain-testis-cancer' gene related to other neoplastic syndromes and tumors.