Comprehensive CCM3 Mutational Analysis in Patients with Syndromic Cerebral Cavernous Malformation

Abstract Cerebral Cavernous Malformation (CCM) is a vascular disease that affects the central nervous system, which familial form is due to autosomal dominant mutations in the genes KRIT1/CCM1, MGC4607/CCM2 and PDCD10/CCM3. Patients affected by the PDCD10 mutations usually have the onset of symptoms at an early age and a more aggressive phenotype. To contribute to knowledge about the disease, we performed clinical, functional, and neuroradiological analyses of the mutations in PDCD10/CCM3 in two patients comparing the findings with five patients with familial form from CCM1/KRIT1 or CCM2/MGC4607 mutations and six patients with sporadic form. In addition, we have evaluated the PDCD10/CCM3 gene expression by qPCR and developed a bioinformatic pipeline to assist in the possible clinical. The two CCM3 patients had an early onset of symptoms and a high lesion burden. Furthermore, the sequencing showed that P1 had a frameshift mutation (c.222delT;p.Asn75ThrfsTer14) and P2 a variant on the splicing region c.475-2A > G (p.A119Gfs*42). The mRNA expression was 4-fold lower in both patients with PDCD10/CCM3 mutation. In silico analysis, the prediction reveals that the frameshift mutation transcript lacks the C-terminal FAT-homology domain compared to the 212 aa-length wild-type PDCD10/CCM3 and preserves the N-terminal dimerization domain. We also demonstrated a related pathway that might explain the interplay between low-grade astrocytomas and PDCD10 CCM, a possible manifestation of the syndromic disease. The two mutations support the understanding of the protein-protein interaction between PDCD10 and several essential cellular proteins that might contribute to the mechanistic understanding of why some individuals with CCM3 have a syndromic phenotype.