[Amyotrophic lateral sclerosis--indications of increased antiretroviral seroreactivity without obvious epidemiology].

Of 25 male and 13 female patients diagnosed as sporadic cases of amyotrophic lateral sclerosis between 1989 and 1992, 17 had reproducible serum antibodies against human foamy virus (HFV = human spuma retrovirus, HSRV). HFV-positive ALS patients had higher IgG3 concentrations than HFV-negatives (P < 0.05) and competed better on maedi-visna retroviral antigen than HFV-negatives or controls (P < 0.05), but did not differ otherwise. Two HFV-positive patients were living in the same building; two other ALS patients lived within 300 m of one another, and three HFV gag reactive men (2 ALS, 1 control) were living in neighbouring villages. These were the closest geographic clusters found among current patients. We summarize recent findings compatible with a pathogenetic role for endogenous and/or exogenous retroviral sequences in adult motor neuron disease, and confirm a male preponderance as well as an inverse correlation between survival time and age at onset.