Heterozygous PNPT1 Variants Cause a Sensory Ataxic Neuropathy

Abstract

Background: Biallelic variants in polyribonucleotide-nucleotidyltransferase-1 (PNPT1) have been associated with a range of phenotypes from syndromic hearing loss to Leigh's syndrome. More recently, heterozygous variants in PNPT1, have been reported in three families with cerebellar ataxia and prominent sensory neuropathy.

Methods: Whole genome sequencing was performed in two families with autosomal dominant sensory ataxic neuropathy (SAN).

Results: Segregating heterozygous splice site (c.2014-3C>G) and nonsense (p.Arg715Ter) variants were detected in both families. All patients initially presented with an isolated SAN clinically and neurophysiologically with subsequent variable cerebellar involvement.

Conclusion: We report two heterozygous PNPT1 variants in two families with a predominant SAN, including the novel p.Arg715Ter. This strengthens the argument of PNPT1 causing dominant disease and highlights a new cause for dominantly inherited SAN.

Keywords: CMT; ataxia; neurogenetics; sensory ataxic neuropathy; spinocerebellar ataxia.