Misclassification and linkage of hereditary sensory and autonomic neuropathy type 1 as Charcot-Marie-Tooth disease, type 2B.

for these populations, we think that it is wiser to admit that the hypothesis of direct contact has not been adequately tested. Why is the B-lineage clade, a clade most common on the western coast of the Americas, not found in Beringia? Why does the B-lineage clade have lower sequence diversity and a different mismatch distribution than do the major A, C, and D clades (as well as others recently documented by T. Schurr and colleagues) in Amerindians? Why are other lineages, not just in the B group, found in Pacific and Amerindian populations? Finally, how do we account for the prehistoric distribution of the sweet potato in Oceania (Yen 1974)? Just as current mtDNA data alone may be insufficient to answer the question of "Neanderthal" gene continuity with modern European populations, the question of whether there was limited gene flow between Native Americans and Oceanic populations is unresolved. Rather than make dogmatic statements, we feel that it is better to encourage the open exploration of this debate , with more genetic markers and the use of data already in the literature. al (1994) Phylogenetic subtypes of human T-lymphotropic virus type 1 and their relations to the anthropological background. The neighbor-joining method: a new method for reconstructing phylogenetic trees. Misclassification and Linkage of Hereditary Sensory and Autonomic Neuropathy Type 1 as Charcot-Marie-Tooth Disease, Type 2B To the Editor: Recently Kwon et al. (1995) published in the Journal their work describing linkage of a single large family with an inherited axonal neuropathy to chromosome 3, which they suggest is a second locus for Charcot-Marie-Tooth (CMT) type 2 and subsequently named "CMT2B." We think that the diagnostic classification of this family as CMT2 is incorrect, since the subjects have a severe sensory neuropathy that fits within the hereditary sensory and autonomic neuropathy (HSAN) type 1 classification of Dyck (1993). Abnormal sensory findings in CMT2 separate it from distal spinal muscular atrophy but are a minor component of clinical symptoms in most CMT patients, as CMT is primarily a motor neuropathy. When Kwon et al. (1995, p. 854) state that "all [patients] had characteristic findings on their physical examinations, including. .. evidence of foot sores that were slow to heal, or amputated limbs related to the poorly healing foot ulcers ," it suggests that a different diagnosis is more appropriate. In our experience collecting data on >950