Hereditary sensory autonomic neuropathy type VI in the age of genetic testing

Background

Hereditary sensory and autonomic neuropathy type VI (HSAN VI) is a rare recessive genetic disorder caused by mutations in the human dystonin (DST) gene. We report a novel homozygous alternate transcript mutation in the DST gene causing a severe neonatal form of HSAN VI.

Patient Description

This baby boy was born with severe hypotonia, respiratory distress, dysmorphic features, and bilateral club feet. Imaging, karyotyping, Prader–Willi assay, spinal muscular atrophy genetic panel and myotonic dystrophy genetic panel were all negative. A comprehensive neuropathy panel detected a homozygous pathogenic variant in the DST gene—alternate transcript NM_015546.4:c.1357G>A (p.Trp4525*). Nerve conduction studies revealed mixed axonal and demyelinating sensorimotor neuropathy, suggesting the possibility of motor involvement in severe forms of this rare condition. The infant ultimately developed sepsis and died from cardiorespiratory arrest. Neuropathological findings of focal and mild spinal nerve axonal degeneration were nonspecific.

Conclusion

Collective analysis of these patients would help to further characterize the spectrum of disease pathology and could provide insight into the neurophysiology and neuropathology of this rare condition.