Mutation Analysis of SLC20A2 and SPP2 as Candidate Genes for Familial Idiopathic Basal Ganglia Calcification

Background: Familial Idiopathic Basal Ganglia Calcification (IBGC) is a rare neurodegenerative disorder which is usually transmitted as an autosomal dominant trait. IBGC is genetically heterogeneous and SLC20A2, on chromosome 8p21.1–8q11.23, is the first gene found in IBGC-affected patients with varied ancestry. On the other hand, several candidate genes for IBGC on chromosome 2q37, including the SPP2 gene, may play a role in inhibiting calcification. Methods: Totally, 22 members of a three generational Iranian family affected by IBGC, with an autosomal dominant pattern of inheritance were included in this study. DNA was extracted from the whole blood using standard salting out method. To find a mutation responsible for IBGC, we sequenced the coding region of SLC20A2 as well as promoter and coding region of SPP2 in the index subject of IBGC-affected family. Results: Pathogenic mutation was found neither in SLC20A2 nor in SPP2. Conclusion: Our results strengthen genetic heterogeneity of this condition. Additional mutation studies are necessary to find a gene or genes responsible for IBGC in this affected family.