Three novel missense mutations in SLC20A2 associated with idiopathic basal ganglia calcification

Background and purpose
Familial idiopathic basal ganglia calcification (FIBGC) is an autosomal dominant condition characterized by symmetric calcification in the basal ganglia and other brain regions. Here, we describe three novel causative mutations in SLC20A2 associated with FIBGC.
Methods
Three independent patients with clinical and neuroradiological findings compatible with FIBGC were analyzed for mutations in SLC20A2 gene. A detailed clinical and neuroradiological evaluation was performed.
Results
We identified the c.188 G>A (p.Gly63Asp) and c.1196 A>C (p.His399Pro) missense changes in two patients presenting with migraine without aura, and the c.187 G>A (p.Gly63Ser) in a man and his sister with bipolar disorder type 2 and cognitive impairment.
Conclusions
Our work further corroborates the extreme phenotypic variability in FIBGC patients, also when the same amino acid residue is mutated. We describe the first patient with a mutation in SLC20A2 and bipolar disorder type 2. Moreover, sequential CT scans in one case documented the progression of brain calcifications.