[Significance of hepatitis B virus antibody in motor neuron disease].

We present here an assumption that hepatitis B virus (HBV) is involved in the pathogenesis of motor neuron disease (MND) in part, because of very high incidence of HBV antibody in patients with MND. In this study HBV antibodies were determined in 34 patients with MND (15 with ALS, 7 with SPMA, 8 with PBP and 4 with PBP+SPMA), and it was revealed that hepatitis B surface antigen (enzyme immunoassay: EIA) was negative in all the patients, whereas hepatitis B surface antibody (HBs-Ab) (EIA) was positive in 25 patients (73.5%) (9 with ALS, 6 with SPMA, 7 with PBP and 3 with PBP+SPMA). In contrast, HBs-Ab was positive only in 2 out of 28 patients with brain infarction (7.1%), and in 1 out of 16 patients with spinocerebellar degeneration (6.3%), both of which were used as control. Of 22 patients with indefinite complaints, none was positive for HBs-Ab. Thus, the number of HBs-Ab positive individuals was significantly (P < 0.001) greater in patients with MND than that in the patients having other disorders of central nervous system. From the above result, we conclude that MND may be partially ascribed to HBV.