12-51915270-T-C

Position:

• chr12-51915270-T-C

Variant summary

Our verdict is Pathogenic. Variant got 17 ACMG points: 17P and 0B. PM1 PM2 PP2 PP3_Strong PP5_Very_Strong

The NM_000020.3(ACVRL1):​c.818T>C​(p.Leu273Pro) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.000000684 in 1,461,834 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. 12/21 in silico tools predict a damaging outcome for this variant. Variant has been reported in ClinVar as Likely pathogenic (★★). Synonymous variant affecting the same amino acid position (i.e. L273L) has been classified as Likely benign.

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 6.8e-7 (0 hom.)
• Consequence: ACVRL1 NM_000020.3 missense
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:4
• Conservation: PhyloP100: 8.01

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 Pathogenic. Variant got 17 ACMG points.

• PM1: In a hotspot region, there are 4 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 0 benign, 2 uncertain in NM_000020.3
• 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, 0.989
• PP5: Variant 12-51915270-T-C is Pathogenic according to our data. Variant chr12-51915270-T-C is described in ClinVar as [Likely_pathogenic]. Clinvar id is 426017.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars. Variant chr12-51915270-T-C is described in Lovd as [Pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
ACVRL1	NM_000020.3	c.818T>C	p.Leu273Pro	missense_variant	7/10	ENST00000388922.9

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
ACVRL1	ENST00000388922.9	c.818T>C	p.Leu273Pro	missense_variant	7/10	1	NM_000020.3	P1

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome AF: 6.84e-7 AC: 1 AN: 1461834 Hom.: 0 Cov.: 32 AF XY: 0.00 AC XY: 0 AN XY: 727212

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: 0.00

Gnomad4 OTH exome AF: 0.0000166

GnomAD4 genome Cov.: 33

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:4

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Pulmonary arterial hypertension related to hereditary hemorrhagic telangiectasia Pathogenic:1

Pathogenic, no assertion criteria provided

literature only

Rare Disease Genomics Group, St George's University of London

-

- -

Telangiectasia, hereditary hemorrhagic, type 2 Pathogenic:1

Likely pathogenic, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Mar 15, 2023

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. Advanced modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) performed at Invitae indicates that this missense variant is expected to disrupt ACVRL1 protein function. ClinVar contains an entry for this variant (Variation ID: 426017). This missense change has been observed in individual(s) with clinical features of hereditary hemorrhagic telangiectasia (PMID: 15712271). It has also been observed to segregate with disease in related individuals. This variant is not present in population databases (gnomAD no frequency). This sequence change replaces leucine, which is neutral and non-polar, with proline, which is neutral and non-polar, at codon 273 of the ACVRL1 protein (p.Leu273Pro). -

Hereditary hemorrhagic telangiectasia Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Laboratory for Molecular Medicine, Mass General Brigham Personalized Medicine

Dec 09, 2014

The p.Leu273Pro variant in ACVRL1 has been reported in 3 individuals with Hereditary Hemorrhagic Telangiectasia (HHT) and segregated with disease in 7 affected relatives from 2 families (Abdalla 2005, Smoot 2009, Westerman 2011). It was absent from large population studies. Computational prediction tools and conservation analysis suggest that the p.Leu273Pro variant may impact the protein, though this information is not predictive enough to determine pathogenicity. In summary, this variant meets our criteria to be classified as pathogenic for hereditary hemorrhagic telangiectasia in an autosomal dominant manner (http://www.partners.org/personalizedmedicine/LMM) based upon segregation studies. -

Cardiovascular phenotype Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Ambry Genetics

Jul 15, 2021

The p.L273P pathogenic mutation (also known as c.818T>C), located in coding exon 6 of the ACVRL1 gene, results from a T to C substitution at nucleotide position 818. The leucine at codon 273 is replaced by proline, an amino acid with similar properties. This mutation was described in a child with pulmonary arteriovenous malformation (PAVM) and was found to track with disease in the affected mother, grandmother, and maternal aunt (Abdalla SA et al. Hum. Mutat., 2005 Mar;25:320-1). In another study, this mutation was also described in a child presenting with pulmonary arterial hypertension and a PAVM; the mutation also tracked in clinically affected family members (Smoot LB et al. Arch. Dis. Child., 2009 Jul;94:506-11). This mutation was identified in a Kenyan male with epistaxis, telangiectasias, and a family history of epistaxis (Kitonyi GW et al. East Afr Med J, 2008 Aug;85:412-6; Westermann CJ et al. Haemophilia, 2011 Jan;17:e244). Based on the supporting evidence, this alteration is interpreted as a disease-causing mutation. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	1.0
BayesDel_addAF	Pathogenic	0.37	D
BayesDel_noAF	Pathogenic	0.30
CADD	Pathogenic	32
DANN	Pathogenic	1.0
DEOGEN2	Pathogenic	0.87	D;.;D
Eigen	Pathogenic	0.81
Eigen_PC	Pathogenic	0.78
FATHMM_MKL	Uncertain	0.97	D
LIST_S2	Pathogenic	0.98	D;D;D
M_CAP	Pathogenic	0.52	D
MetaRNN	Pathogenic	0.99	D;D;D
MetaSVM	Uncertain	0.058	D
MutationAssessor	Benign	2.0	M;.;.
MutationTaster	Benign	1.0	D;D;D
PrimateAI	Pathogenic	0.92	D
PROVEAN	Pathogenic	-6.8	D;D;D
REVEL	Pathogenic	0.78
Sift	Pathogenic	0.0	D;D;D
Sift4G	Pathogenic	0.0	D;D;D
Polyphen		1.0	D;.;D
Vest4		0.99
MutPred		0.96		Gain of disorder (P = 0.0157);.;.;
MVP		0.97
MPC		2.0
ClinPred		1.0	D
GERP RS		5.3
Varity_R		0.99
gMVP		1.0

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.0		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: rs1085307409; hg19: chr12-52309054;