Identification of a Novel de Novo Variant in the SYT2 Gene Causing a Rare Type of Distal Hereditary Motor Neuropathy.

OBJECTIVE

To report the first de novo missense mutation in the SYT2 gene causing distal hereditary motor neuropathy.

METHODS

Genetic testing was carried out, including clinical exome sequencing for the proband and Sanger sequencing for the proband and his parents. We described the clinical and electrophysiological features found in the patient.

RESULTS

We reported a proband with a new de novo missense mutation, c.917C>T (p.Ser306Leu), in the C2B domain of SYT2. The clinical presentation was similar to that of phenotypes described in previous studies. A notable feature in our study was normal electrophysiological testing results of the patient.

CONCLUSIONS

In this study we reinforced the association between SYT2 mutations and distal hereditary motor neuropathy. We also described the clinical presentation of the patient carrying this pathogenic variant and provided unusual results of electrophysiological testing. The results showed that a diagnosis of SYT2-associated neuropathy should be based on the similarity of clinical manifestations, rather than the results of electrophysiological testing.