Cortical myoclonus and epilepsy in a family with a new SLC20A2 mutation

Antonietta Coppola,Sanjay M Sisodiya,Laura Hernandez-Hernandez,Carla Cordivari,Blake Hale,Simona Balestrini,Nicholas Moran,S Krithika

doi:10.1007/s00415-020-09821-4

Abstract

Idiopathic basal ganglia calcification (IBGC) or primary familial brain calcification is a rare genetic condition characterized by an autosomal dominant inheritance pattern and the presence of bilateral calcifications in the basal ganglia, thalami, cerebellum and cerebral subcortical white matter. The syndrome is genetically and phenotypically heterogeneous. Causal mutations have been identified in four genes: SLC20A2, PDGFRB, PDGFB and XPR1. A variety of progressive neurological and psychiatric symptoms have been described, including cognitive impairment, movement disorders, bipolar disorder, chronic headaches and migraine, and epilepsy. Here we describe a family with a novel SLC20A2 mutation mainly presenting with neurological symptoms including cortical myoclonus and epilepsy. While epilepsy, although rare, has been reported in patients with IBGC associated with SLC20A2 mutations, cortical myoclonus seems to be a new manifestation.

Highlights

Idiopathic basal ganglia calcification (IBGC) or primary familial brain calcification (PFBC) is a rare autosomal dominant genetic condition characterized by the hallmark of bilateral calcifications in the basal ganglia, thalami, cerebellum and subcortical white matter
While epilepsy has been reported in seven cases with IBGC and SLC20A2 mutations [1, 8, 11, 14, 25, 30], cortical myoclonus has not been reported to our knowledge
Mutations in SLC20A2 account for the majority of cases with IBGC [11, 19]

Summary

Introduction

Idiopathic basal ganglia calcification (IBGC) or primary familial brain calcification (PFBC) is a rare autosomal dominant genetic condition characterized by the hallmark of bilateral calcifications in the basal ganglia, thalami, cerebellum and subcortical white matter. Mutations in SLC20A2 seem to be the major cause of IBGC, accounting for as many as 41% of the familial cases [11]. This gene encodes the inorganic phosphate (Pi) transporter PiT2 which is expressed ubiquitously in the brain, mainly in the sites where calcifications tend to occur (the globus pallidus, thalamus and cerebellum) [6]. While epilepsy has been reported in seven cases with IBGC and SLC20A2 mutations [1, 8, 11, 14, 25, 30], cortical myoclonus has not been reported to our knowledge

Methods

Discussion

Findings

Compliance with ethical standards