A splice site mutation causing exon 6 skipping in SLC20A2 gene in a primary familial brain calcification family

Abstract

Background: Primary familial brain calcification (PFBC) is a rare degenerative disease characterized by symmetrical bilateral calcinosis in the basal ganglia and other brain regions. It has an autosomal dominant inheritance pattern in most cases and exhibits genetic heterogeneity. Previous studies reported that SLC20A2, PDGFRB, PDGFB, XPR1 and MYORG are associated with PFBC, with SLC20A2 the main culprit. However, other mutations may also cause PFBC. Here, we performed a study to reveal the contributing mutations that gave rise to PFBC in a Chinese PFBC family.

Methods: We recruited a PFBC family consisting of eight patients and eight healthy family members across three generations. Whole-exome sequencing, Sanger sequencing and RT-PCR were used to detect the genetic mutations.

Results: Whole-exome sequencing revealed that c.730 + 1G > A of SLC20A2 was the candidate pathogenic mutation for the proband in this family. Genomic DNA PCR amplification and Sanger sequencing confirmed that all the patients from the family carried this mutation, while the healthy subjects in the family did not. Complementary DNA (cDNA) PCR amplification and Sanger sequencing confirmed that the patients had a mutation that caused exon 6 skipping in SLC20A2.

Conclusion: We identified a SLC20A2 splicing variant (c.730 + 1G > A) in a PFBC family. This mutation led to an alternative splicing event that skipped exon 6 in SLC20A2.

Keywords: Brain calcification; Idiopathic basal ganglia calcification; Primary familial brain calcification; SLC20A2; Splicing variant.