Hereditary sensory neuropathy type I (HSN1) is the most common dominantly inherited degenerative disorder of sensory neurons. The gene mutation was mapped to chromosome 9 in a large Australian family, descended from an ancestor from southern England who was a convict. Dawkins et al. recently reported gene mutations in the SPTLC1 gene, in this and other families. The first description of hereditary sensory neuropathy, by Hicks, was in a family from London and Exeter. To determine if the families in the present study that have SPTLC1 mutations are related to English families with HSN1 and, possibly, to the family studied by Hicks, we performed haplotype analysis of four Australian families of English extraction, four English families, and one Austrian family. Three Australian families of English extraction and three English families (two of whom have been described elsewhere) had the 399T→G SPTLC1 mutation, the same chromosome 9 haplotype, and the same phenotype. The Australian and English families may therefore have a common founder who, on the basis of historical information, has been determined to have lived in southern England prior to 1800. The sensorimotor neuropathy phenotype caused by the 399T→G SPTLC1 mutation is the same as that reported by Campbell and Hoffman and, possibly, the same as that originally described by Hicks.