NM_194454.3:c.1A>G

Variant names:

• chr7-92242135-T-C
• rs1554539120
• NM_194454.3:c.1A>G

Variant summary

Our verdict is Pathogenic. Variant got 12 ACMG points: 12P and 0B. PM2 PP3_Moderate PP5_Very_Strong

The NM_194454.3(KRIT1):​c.1A>G​(p.Met1?) variant causes a start lost, splice region change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000143 in 1,400,016 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. 1/1 splice prediction tools predicting alterations to normal splicing. Variant has been reported in ClinVar as Likely pathogenic (★★).

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000014 (0 hom.)
• Consequence: KRIT1 NM_194454.3 start_lost, splice_region
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:3
• Conservation: PhyloP100: 7.34

Genes affected

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]

ENSG00000289027 (HGNC:):

ACMG classification

Verdict is Pathogenic. Variant got 12 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP3: Splicing scoreres supports a deletorius effect: Scorers claiming Pathogenic: max_spliceai. No scorers claiming Uncertain. No scorers claiming Benign.
• PP5: Variant 7-92242135-T-C is Pathogenic according to our data. Variant chr7-92242135-T-C is described in ClinVar as [Likely_pathogenic]. Clinvar id is 468215.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
KRIT1	NM_194454.3	c.1A>G	p.Met1?	start_lost, splice_region_variant	Exon 4 of 19	ENST00000394505.7	NP_919436.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
KRIT1	ENST00000394505.7	c.1A>G	p.Met1?	start_lost, splice_region_variant	Exon 4 of 19	1	NM_194454.3	ENSP00000378013.2
ENSG00000289027	ENST00000692281.1	c.1A>G	p.Met1?	start_lost, splice_region_variant	Exon 4 of 26			ENSP00000510568.1
ENSG00000285953	ENST00000458493.6	c.1A>G	p.Met1?	start_lost, splice_region_variant	Exon 3 of 20	4		ENSP00000396352.2

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 0.00000143 AC: 2 AN: 1400016 Hom.: 0 Cov.: 23 AF XY: 0.00000286 AC XY: 2 AN XY: 700378

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00000189

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 32

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:3

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

not provided Pathogenic:2

May 23, 2024

GeneDx

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Initiation codon variant in a gene for which loss of function is a known mechanism of disease; Not observed at significant frequency in large population cohorts (gnomAD); This variant is associated with the following publications: (PMID: 34556564) -

Feb 15, 2017

PreventionGenetics, part of Exact Sciences

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Cerebral cavernous malformation Pathogenic:1

Jun 24, 2024

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change affects the initiator methionine of the KRIT1 mRNA. The next in-frame methionine is located at codon 94. This variant is not present in population databases (gnomAD no frequency). Disruption of the initiator codon has been observed in individual(s) with cerebral cavernous malformations (PMID: 34556564; Invitae). It has also been observed to segregate with disease in related individuals. ClinVar contains an entry for this variant (Variation ID: 468215). Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant may create or strengthen a splice site. For these reasons, this variant has been classified as Pathogenic. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.45	D
BayesDel_noAF	Pathogenic	0.41
CADD	Pathogenic	33
DANN	Uncertain	0.99
DEOGEN2	Benign	0.27	.;T;T;T;T;.;T;T;.;T;.;T;T;T;.;.;.;.
Eigen	Uncertain	0.57
Eigen_PC	Uncertain	0.62
FATHMM_MKL	Pathogenic	1.0	D
LIST_S2	Uncertain	0.90	D;D;.;.;.;D;D;D;D;D;D;D;D;D;D;D;D;.
M_CAP	Pathogenic	0.79	D
MetaRNN	Pathogenic	0.99	D;D;D;D;D;D;D;D;D;D;D;D;D;D;D;D;D;D
MetaSVM	Uncertain	-0.12	T
PROVEAN	Benign	-1.0	.;N;N;N;N;N;D;D;D;D;D;D;D;D;D;D;D;D
REVEL	Uncertain	0.60
Sift	Pathogenic	0.0	.;D;D;D;D;D;D;D;D;D;D;D;D;D;D;D;.;.
Sift4G	Pathogenic	0.0	.;D;D;D;D;D;D;.;.;D;.;.;.;D;D;D;D;.
Polyphen		0.0020	.;B;B;B;B;.;.;.;.;.;.;.;.;.;.;.;.;.
Vest4		0.90, 0.93, 0.91, 0.88
MutPred		1.0		Loss of helix (P = 0.079);Loss of helix (P = 0.079);Loss of helix (P = 0.079);Loss of helix (P = 0.079);Loss of helix (P = 0.079);Loss of helix (P = 0.079);Loss of helix (P = 0.079);Loss of helix (P = 0.079);Loss of helix (P = 0.079);Loss of helix (P = 0.079);Loss of helix (P = 0.079);Loss of helix (P = 0.079);Loss of helix (P = 0.079);Loss of helix (P = 0.079);Loss of helix (P = 0.079);Loss of helix (P = 0.079);Loss of helix (P = 0.079);Loss of helix (P = 0.079);
MVP		0.90
ClinPred		0.99	D
GERP RS		6.0
Varity_R		0.74
gMVP		0.59

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.99		Details are displayed if max score is > 0.2
DS_AG_spliceai		0.99		Position offset: -1

Find out detailed SpliceAI scores and Pangolin per-transcript scores at spliceailookup.broadinstitute.org

Publications

LitVar

Other links and lift over

dbSNP: rs1554539120; hg19: chr7-91871449;