rs1060503234

Positions:

• chr12-51913303-G-T

Variant summary

Our verdict is Likely pathogenic. Variant got 8 ACMG points: 8P and 0B. PM2 PP2 PP3_Strong PP5

The NM_000020.3(ACVRL1):​c.266G>T​(p.Cys89Phe) variant causes a missense change. The variant allele was found at a frequency of 0.000000686 in 1,458,716 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars).

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 6.9e-7 (0 hom.)
• Consequence: ACVRL1 NM_000020.3 missense
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications P:1 U:2
• Conservation: PhyloP100: 5.91

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 Likely_pathogenic. Variant got 8 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP2: Missense variant in gene, where missense usually causes diseases (based on misZ statistic), ACVRL1. . Gene score misZ 2.4458 (greater than the threshold 3.09). Trascript score misZ 3.182 (greater than threshold 3.09). GenCC has associacion of gene with hereditary hemorrhagic telangiectasia, telangiectasia, hereditary hemorrhagic, type 2.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.993
• PP5: Variant 12-51913303-G-T is Pathogenic according to our data. Variant chr12-51913303-G-T is described in ClinVar as [Conflicting_classifications_of_pathogenicity]. Clinvar id is 411299.We mark this variant Likely_pathogenic, oryginal submissions are: {Likely_pathogenic=1, Uncertain_significance=2}.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
ACVRL1	NM_000020.3	c.266G>T	p.Cys89Phe	missense_variant	3/10	ENST00000388922.9	NP_000011.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
ACVRL1	ENST00000388922.9	c.266G>T	p.Cys89Phe	missense_variant	3/10	1	NM_000020.3	ENSP00000373574	P1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 6.86e-7 AC: 1 AN: 1458716 Hom.: 0 Cov.: 32 AF XY: 0.00 AC XY: 0 AN XY: 725384

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: 9.00e-7

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 32

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 Pathogenic:1

Likely pathogenic, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Jul 11, 2022

In summary, the currently available evidence indicates that the variant is pathogenic, but additional data are needed to prove that conclusively. Therefore, this variant has been classified as Likely Pathogenic. This variant disrupts the p.Cys89 amino acid residue in ACVRL1. Other variant(s) that disrupt this residue have been observed in individuals with ACVRL1-related conditions (Invitae), which suggests that this may be a clinically significant amino acid residue. This variant affects a cysteine residue located within the ACVRL1 protein ectodomain. Cysteine residues in this domain of ACVRL1 are involved in the formation of disulfide bridges critical for protein structure and stability (PMID: 22028876, 22718755, 22799562). In addition, missense substitutions within the ACVRL1 ectodomain affecting cysteine residues are overrepresented in patients with HHT (PMID: 20501893, 26176610 and www.hhtmutation.org). Algorithms developed to predict the effect of missense changes on protein structure and function (SIFT, PolyPhen-2, Align-GVGD) all suggest that this variant is likely to be disruptive. ClinVar contains an entry for this variant (Variation ID: 411299). This missense change has been observed in individuals with hereditary hemorrhagic telangiectasia (Invitae). This variant is not present in population databases (gnomAD no frequency). This sequence change replaces cysteine, which is neutral and slightly polar, with phenylalanine, which is neutral and non-polar, at codon 89 of the ACVRL1 protein (p.Cys89Phe). -

ACVRL1-related disorder Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

PreventionGenetics, part of Exact Sciences

Dec 29, 2022

The ACVRL1 c.266G>T variant is predicted to result in the amino acid substitution p.Cys89Phe. To our knowledge, this variant has not been reported in the literature or in a large population database (http://gnomad.broadinstitute.org), indicating this variant is rare. Of note, other missense variants at the same amino acid (p.Cys89Arg and p.Cys89Tyr) have been reported in patients with hereditary hemorrhagic telangiectasia (HHT) (Table S1 in McDonald et al. 2020. PubMed ID: 32300199; Olivieri et al. 2007. PubMed ID: 17786384). Although we suspect that the c.266G>T (p.Cys89Phe) variant may be pathogenic, at this time, the clinical significance of this variant is uncertain due to the absence of conclusive functional and genetic evidence. -

not provided Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

GeneDx

Apr 05, 2023

Has not been previously published as pathogenic or benign to our knowledge; Not observed at significant frequency in large population cohorts (gnomAD); In silico analysis supports that this missense variant has a deleterious effect on protein structure/function -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.94
BayesDel_addAF	Pathogenic	0.52	D
BayesDel_noAF	Pathogenic	0.51
CADD	Pathogenic	28
DANN	Uncertain	0.99
DEOGEN2	Pathogenic	0.94	.;D;.;.
Eigen	Pathogenic	0.71
Eigen_PC	Uncertain	0.66
FATHMM_MKL	Uncertain	0.95	D
LIST_S2	Benign	0.74	T;T;T;T
M_CAP	Pathogenic	0.92	D
MetaRNN	Pathogenic	0.99	D;D;D;D
MetaSVM	Pathogenic	0.89	D
MutationAssessor	Uncertain	2.2	.;M;.;.
MutationTaster	Benign	1.0	D;D;D
PrimateAI	Uncertain	0.51	T
PROVEAN	Pathogenic	-8.9	D;D;D;D
REVEL	Pathogenic	0.90
Sift	Pathogenic	0.0	D;D;D;D
Sift4G	Pathogenic	0.0	D;D;D;D
Polyphen		1.0	.;D;.;.
Vest4		0.83, 0.86
MutPred		0.98		Gain of sheet (P = 0.0221);Gain of sheet (P = 0.0221);.;.;
MVP		1.0
MPC		1.9
ClinPred		1.0	D
GERP RS		5.8
Varity_R		0.98
gMVP		1.0

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.050		Details are displayed if max score is > 0.2

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

Publications

LitVar

Other links and lift over

dbSNP: rs1060503234; hg19: chr12-52307087;