Cluster of acute infantile spinal muscular atrophy (Werdnig-Hoffmann disease) in a limited area of Reunion Island.

A retrospective study of Werdnig-Hoffmann disease (spinal muscular atrophy type I) was undertaken on Reunion Island. Nineteen WH cases born between 1969 and 1980 were recorded belonging to thirteen sibships of the European population of the island. Genealogical analysis, going back to the XVIIth century (1642), showed a relationship among the 13 families, which were derived from a common ancestral pair. A founder effect is the most probable explanation for the concentration of Werdnig-Hoffmann disease in the area.