SYT2-Related Disease: A Case-Based Review

Synaptotagmin-2-related disease is an ultrarare entity, characterized by distal muscle atrophy in the lower limbs, foot deformities and, in some cases, neonatal hypotonia. Most mutations are concentrated in the C2B domain, critical for the protein's function. Here, our objective is to review clinical, electrophisiological and pathological aspects of this disease.

We describe a previously unreported variant, comparing it with another 27 cases described in the literature.

A 14-year-old boy was born with neonatal hypotonia, weak cry, and dysphonia. During childhood, he had recurrent respiratory infections, delayed motor development, and developed glaucoma. Creatine phosphokinase level was 501 U/L; EMG showed reduced compound muscle action potential, myopathic findings, and incremental response. A comprehensive next-generation sequence panel revealed a homozygous variant in the SYT2 gene.

The data summarized here and our case provide a general characterization of the phenotypic spectrum of SYT2-related disease and point out to its electrophysiological and pathological features. We discuss the intriguing aspects of a neuromuscular junction disease considered as a distal hereditary motor neuropathy.