rs772776468

Positions:

• chr12-51913967-C-A
• chr12-51913967-C-T

Variant summary

Our verdict is Uncertain significance. Variant got 2 ACMG points: 3P and 1B. PM2 PP5 BP4

The NM_000020.3(ACVRL1):​c.526-7C>A variant causes a splice region, splice polypyrimidine tract, intron change involving the alteration of a non-conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a benign outcome for this variant. 2/3 splice prediction tools predict no significant impact on normal splicing. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars).

• Frequency: Genomes: not found (cov: 33)
• Consequence: ACVRL1 NM_000020.3 splice_region, splice_polypyrimidine_tract, intron
• Scores: Splicing: ADA: 0.01674
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications P:1 U:2
• Conservation: PhyloP100: -0.0880

Genes affected

ACVRL1 (HGNC:175): (activin A receptor like type 1) This gene encodes a type I cell-surface receptor for the TGF-beta superfamily of ligands. It shares with other type I receptors a high degree of similarity in serine-threonine kinase subdomains, a glycine- and serine-rich region (called the GS domain) preceding the kinase domain, and a short C-terminal tail. The encoded protein, sometimes termed ALK1, shares similar domain structures with other closely related ALK or activin receptor-like kinase proteins that form a subfamily of receptor serine/threonine kinases. Mutations in this gene are associated with hemorrhagic telangiectasia type 2, also known as Rendu-Osler-Weber syndrome 2. [provided by RefSeq, Jul 2008]

ACMG classification

Verdict is Uncertain_significance. Variant got 2 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 12-51913967-C-A is Pathogenic according to our data. Variant chr12-51913967-C-A is described in ClinVar as [Conflicting_classifications_of_pathogenicity]. Clinvar id is 533344.We mark this variant Likely_pathogenic, oryginal submissions are: {Likely_pathogenic=1, Uncertain_significance=2}.
• BP4: Computational evidence support a benign effect (BayesDel_noAF=-0.72). . Strength limited to SUPPORTING due to the PP5.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
ACVRL1	NM_000020.3	c.526-7C>A		splice_region_variant, splice_polypyrimidine_tract_variant, intron_variant		ENST00000388922.9	NP_000011.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
ACVRL1	ENST00000388922.9	c.526-7C>A		splice_region_variant, splice_polypyrimidine_tract_variant, intron_variant		1	NM_000020.3	ENSP00000373574	P1

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome Cov.: 33

GnomAD4 genome Cov.: 33

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Pathogenic:1 Uncertain:2

Revision: criteria provided, conflicting classifications

Submissions by phenotype

Telangiectasia, hereditary hemorrhagic, type 2 Uncertain:2

Uncertain significance, criteria provided, single submitter	clinical testing	Labcorp Genetics (formerly Invitae), Labcorp	Aug 10, 2023	Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant may disrupt the consensus splice site. In summary, the available evidence is currently insufficient to determine the role of this variant in disease. Therefore, it has been classified as a Variant of Uncertain Significance. ClinVar contains an entry for this variant (Variation ID: 533344). This sequence change falls in intron 4 of the ACVRL1 gene. It does not directly change the encoded amino acid sequence of the ACVRL1 protein. This variant is not present in population databases (gnomAD no frequency). This variant has been observed in individual(s) with hereditary hemorrhagic telangiectasia (Invitae). -
Uncertain significance, criteria provided, single submitter	clinical testing	Department of Clinical Genetics, Copenhagen University Hospital, Rigshospitalet	Aug 01, 2021	- -

Cardiovascular phenotype Pathogenic:1

Likely pathogenic, criteria provided, single submitter

clinical testing

Ambry Genetics

Apr 27, 2022

The c.526-7C>A intronic variant results from a C to A substitution 7 nucleotides upstream from coding exon 4 in the ACVRL1 gene. The variant has been detected in a family with features of hereditary hemorrhagic telangiectasia (Ambry internal data). This variant is considered to be rare based on population cohorts in the Genome Aggregation Database (gnomAD). This nucleotide position is not well conserved in available vertebrate species. In silico splice site analysis predicts that this alteration may weaken the native splice acceptor site. RNA studies have demonstrated that this alteration results in abnormal splicing in the set of samples tested (Ambry internal data). Based on the majority of available evidence to date, this variant is likely to be pathogenic. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.72
CADD	Benign	6.7
DANN	Benign	0.63

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Benign	0.017
dbscSNV1_RF	Benign	0.15
SpliceAI score (max)		0.33		Details are displayed if max score is > 0.2
DS_AL_spliceai		0.33		Position offset: 7

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

Publications

LitVar

Other links and lift over

dbSNP: rs772776468; hg19: chr12-52307751;