A novel non-sense mutation in TDP2 causes spinocerebellar ataxia autosomal recessive 23 accompanied by bilateral upward gaze; report of a case and review of the literature.

Pathogenic mutations in TDP2, encoding tyrosyl DNA phosphodiesterase 2, cause Spinocerebellar Ataxia autosomal recessive 23 (SCAR23). It is a rare autosomal recessive disorder and mainly has been reported in the European population. Thus far, merely eight patients harboring four TDP2 variants have been reported in the literature. In this study, a novel pathogenic variant (NM_016614: c.4G > T, p.Glu2*) was identified by Whole-Exome and confirmed by Sanger sequencing. The proband has both intellectual and developmental delay, dysphasia, elbow contracture, and upward gaze. The elbow contracture has not been previously described in previous SCAR23 cases. Lastly, we briefly review the phenotypic features of the patients with SCAR23 in the literature.