HSAN-VI: A spectrum disorder based on dystonin isoform expression.

Hereditary sensory and autonomic neuropathy (HSAN-VI) is a recessive genetic disorder that arises because of mutations in the human dystonin gene (, previously known as ). Although initial characterization of HSAN-VI reported it as a sensory neuropathy that was lethal in infancy, we now know of a number of heterozygous mutations in that result in milder forms of the disease. Akin to what we observe in the mouse model ( ), we believe that the heterogeneity of HSAN-VI can be attributed to a number of dystonin isoforms that the mutation affects. Lack of neuronal isoform dystonin-a2 is likely the universal determinant of HSAN-VI because all reported human cases are null for this isoform, as are all mouse alleles. Compensatory mechanisms by intact dystonin-a isoforms also likely play a role in regulating disease severity, although we have yet to determine what specific effect dystonin-a1 and dystonin-a3 have on the pathogenesis of HSAN-VI.