Mutation Prevalence of Cerebral Cavernous Malformation Genes in Spanish Patients

Abstract

ObjectiveTo study the molecular genetic and clinical features of cerebral cavernous malformations (CCM) in a cohort of Spanish patients.MethodsWe analyzed the CCM1, CCM2, and CCM3 genes by MLPA and direct sequencing of exons and intronic boundaries in 94 familial forms and 41 sporadic cases of CCM patients of Spanish extraction. When available, RNA studies were performed seeking for alternative or cryptic splicing.ResultsA total of 26 pathogenic mutations, 22 of which predict truncated proteins, were identified in 29 familial forms and in three sporadic cases. The repertoire includes six novel non-sense and frameshift mutations in CCM1 and CCM3. We also found four missense mutations, one of them located at the third NPXY motif of CCM1 and another one that leads to cryptic splicing of CCM1 exon 6. We found four genomic deletions with the loss of the whole CCM2 gene in one patient and a partial loss of CCM1and CCM2 genes in three other patients. Four families had mutations in CCM3. The results include a high frequency of intronic variants, although most of them localize out of consensus splicing sequences. The main symptoms associated to clinical debut consisted of cerebral haemorrhage, migraines and epileptic seizures. The rare co-occurrence of CCM with Noonan and Chiari syndromes and delayed menarche is reported.ConclusionsAnalysis of CCM genes by sequencing and MLPA has detected mutations in almost 35% of a Spanish cohort (36% of familial cases and 10% of sporadic patients). The results include 13 new mutations of CCM genes and the main clinical symptoms that deserves consideration in molecular diagnosis and genetic counselling of cerebral cavernous malformations.

Concern regarding classification of c.703G>A/p.Gly235Arg as a novel missense variant in KRIT1 gene

“…These results strongly support its pathogenic role and suggest that the variant, deposited in the Leiden Open Variation Database (https://databases.lovd.nl/ shared/variants/0000369761#00023953) as "likely pathogenic" by the authors, should be classified as "pathogenic". It is worth noting that other examples of KRIT1 point mutations in the coding sequence, which do not lead to missense variations but activate a cryptic splice site motif, have been previously reported (Mondéjar et al, 2014;Riant, Bergametti, Ayrignac, Boulday, & Tournier-Lasserve, 2010;Verlaan, Siegel, & Rouleau, 2002). Interestingly, the c.703G>A variant, identified by our group, results in the same frameshift and truncated protein of 201 amino acids as the variant c.601C>G in Exon 8 (previously reported as p.Gln201Glu), described by Verlaan et al (2002), further supporting its pathogenicity.…”

Structural Basis for the Disruption of the Cerebral Cavernous Malformations 2 (CCM2) Interaction with Krev Interaction Trapped 1 (KRIT1) by Disease-associated Mutations

“…Similarly, the KRIT1 L238F mutation was previously reported in one family (42). Finally, the pathogenic mechanism of the KRIT1 D281G mutation was reported to be through the introduction of a new, alternative splice donor site (14). The clinical significance of the remaining missense mutations listed in Table 1 (Fig.…”

Correlation of the venous angioarchitecture of multiple cerebral cavernous malformations with familial or sporadic disease: a susceptibility-weighted imaging study with 7-Tesla MRI

“…However, based on the distinct pathomechanisms suspected to be involved in the formation of sporadic and familial CCMs (venous malformation or developmental venous anomaly [DVA] 29 -associated formation 2 or lossof-function mutation [germline or somatic] in 1 of the 3 CCM genes with consecutive endothelial dysfunction, 33 respectively), specific differences in local venous angioarchitecture 6,21,25 between these forms of multiple CCMs are expected to be detectable. This has not been systematically studied.…”