Our verdict is Pathogenic. The variant received 14 ACMG points: 14P and 0B. PM2PP3_StrongPP5_Very_Strong
The ENST00000475770.6(KRIT1):n.960G>C variant causes a non coding transcript exon change involving the alteration of a conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Likely pathogenic (★★).
KRIT1 (HGNC:1573): (KRIT1 ankyrin repeat containing) This gene encodes a protein containing four ankyrin repeats, a band 4.1/ezrin/radixin/moesin (FERM) domain, and multiple NPXY sequences. The encoded protein is localized in the nucleus and cytoplasm. It binds to integrin cytoplasmic domain-associated protein-1 alpha (ICAP1alpha), and plays a critical role in beta1-integrin-mediated cell proliferation. It associates with junction proteins and RAS-related protein 1A (Rap1A), which requires the encoded protein for maintaining the integrity of endothelial junctions. It is also a microtubule-associated protein and may play a role in microtubule targeting. Mutations in this gene result in cerebral cavernous malformations. Multiple alternatively spliced transcript variants have been found for this gene. [provided by RefSeq, Sep 2009]
KRIT1 Gene-Disease associations (from GenCC):
cerebral cavernous malformation 1
Inheritance: AD Classification: DEFINITIVE, STRONG Submitted by: G2P, Genomics England PanelApp, Ambry Genetics, Labcorp Genetics (formerly Invitae)
famililal cerebral cavernous malformations
Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
Our verdict: Pathogenic. The variant received 14 ACMG points.
PM2
Very rare variant in population databases, with high coverage;
PP3
Splicing predictors support a deleterious effect. Scorers claiming Pathogenic: dbscSNV1_ADA, dbscSNV1_RF, max_spliceai. No scorers claiming Uncertain. No scorers claiming Benign.
PP5
Variant 7-92234924-C-G is Pathogenic according to our data. Variant chr7-92234924-C-G is described in ClinVar as Pathogenic/Likely_pathogenic. ClinVar VariationId is 536122.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.
For these reasons, this variant has been classified as Pathogenic. Donor and acceptor splice site variants typically lead to a loss of protein function (PMID: 16199547), and loss-of-function variants in KRIT1 are known to be pathogenic (PMID: 10508515, 11222804, 12404106). A different variant affecting this nucleotide (c.730-1G>A) has been reported in individuals and families affected with cerebral cavernous malformations, and has been determined to be pathogenic (PMID: 11222804, 24689081, 23584803). This suggests that this nucleotide is important for normal RNA splicing, and that other variants at this position may also be pathogenic. Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant may disrupt the consensus splice site, but this prediction has not been confirmed by published transcriptional studies. This variant has not been reported in the literature in individuals with a KRIT1-related disease. This variant is not present in population databases (ExAC no frequency). This sequence change affects an acceptor splice site in intron 9 of the KRIT1 gene. It is expected to disrupt RNA splicing and likely results in an absent or disrupted protein product. -