Natura non facit saltus in anti-ganglioside antibody-mediated neuropathies.

Natura non facit saltus (Latin for "nature does not make jumps") is a maxim expressing the idea that natural things and properties change gradually, in a continuum, rather than suddenly. In biomedical sciences, for taxonomic purposes, we make jumps that emphasize differences more than similarities. Among the dysimmune neuropathies, 2 disorders, characterized by the presence of antibodies to gangliosides GM1 and GD1a and a peculiar, exclusive motor involvement, have been identified: acute motor axonal neuropathy (AMAN) and multifocal motor neuropathy (MMN). However, anti-GM1 or -GD1a antibodies are also associated with acute motor and sensory axonal motor neuropathy (AMSAN). We review the results of recent clinical and experimental studies showing that AMAN and MMN are not exclusively motor. We discuss the possible explanations for the greater resistance of sensory fibers to antibody attack to finally suggest that AMAN, AMSAN, and MMN belong to a continuous spectrum with a common pathophysiological mechanism.