LATE-ONSET HMSN 2: FURTHER EVIDENCE OF GENETIC HETEROGENEITY

Abstract

In this issue of Neurology ®, Bennett and others1 describe the clinical and electrophysiologic features, mode of inheritance, and lack of association with genes known to cause hereditary motor sensory neuropathy 2 (HMSN 2) (also called Charcot Marie Tooth 2 [CMT 2]). Six kindreds with inherited axonal polyneuropathy of late onset are described. The disorder was inherited as an autosomal dominant trait in two and by unknown transmission in the other four. The authors conclude that these are late onset forms of inherited axonal neuropathies and that “the genetic causes remain unknown and genetic heterogeneity… is likely.” Recognizing that specific treatment is not available for HMSN (1, 2, or other), should neurologists be interested in these descriptions? I suggest four reasons. First, it is new medical information. True, many of us have previously encountered many patients with HMSN 2 who had late symptomatic onset, but putative genes were not excluded. Whether late onset will remain a characteristic feature will need to be ascertained later. The second reason is that the studies provide further scientific evidence of genetic heterogeneity …