1-173907528-C-T

Position:

• chr1-173907528-C-T

Variant summary

Our verdict is Pathogenic. Variant got 11 ACMG points: 11P and 0B. PM2_Supporting PM4 PS4 PP1_Moderate PP3 PP4

This summary comes from the ClinGen Evidence Repository: The NM_000488.3(SERPINC1):c.1154-14G>A variant is completely absent from gnomAD v2.1.1 and v3.1, meeting criteria for PM2_supporting. More than 20 probands across publications and internal laboratory data meet AT deficiency phenotype criteria and therefore, PS4_Very Strong is applied. 6 segregations across 4 families are counted in the literature (PMIDs: 7981186, 15164384, 7949130, 32686144), so PP1_Moderate is applied. SpliceAI predicts a cryptic acceptor splice site at -2bp with a score of 0.5. At least 2 publications (PMID:7949130, PMID:30046692) show experimental evidence of alternative splicing in patients due to the variant and therefore, PP3 is applied. The splicing aberration results in addition of 12bp of intron 4 into exon 5 of SERPINC1, increasing the protein length by 4 amino acids. This region is noted to be important for the folding and polymerization of the protein. Therefore, PM4 is applied. In summary, this variant meets criteria to be classified as pathogenic. ACMG/AMP criteria applied, as specified by the Thrombosis Variant Curation Expert Panel for SERPINC1: PS4_Very Strong, PM4, PP1_Moderate, PP3, PM2_Supporting. LINK:https://erepo.genome.network/evrepo/ui/classification/CA16609956/MONDO:0013144/084

• Frequency:
  • Genomes: not found (cov: 31)
  • Exomes 𝑓: 6.9e-7 (0 hom.)
• Consequence: SERPINC1 NM_000488.4 intron
• Clinical Significance: Pathogenic reviewed by expert panel P:3
• Conservation: PhyloP100: 0.221

Genes affected

SERPINC1 (HGNC:775): (serpin family C member 1) The protein encoded by this gene, antithrombin III, is a plasma protease inhibitor and a member of the serpin superfamily. This protein inhibits thrombin as well as other activated serine proteases of the coagulation system, and it regulates the blood coagulation cascade. The protein includes two functional domains: the heparin binding-domain at the N-terminus of the mature protein, and the reactive site domain at the C-terminus. The inhibitory activity is enhanced by the presence of heparin. Numerous mutations have been identified for this gene, many of which are known to cause antithrombin-III deficiency which constitutes a strong risk factor for thrombosis. A reduction in the serum level of this protein is associated with severe cases of Coronavirus Disease 19 (COVID-19). [provided by RefSeq, Sep 2020]

ACMG classification

Verdict is Pathogenic. Variant got 11 ACMG points.

• PS4: For more information check the summary or visit ClinGen Evidence Repository.
• PM2: For more information check the summary or visit ClinGen Evidence Repository.
• PM4: For more information check the summary or visit ClinGen Evidence Repository.
• PP1: For more information check the summary or visit ClinGen Evidence Repository.
• PP3: For more information check the summary or visit ClinGen Evidence Repository.
• PP4: For more information check the summary or visit ClinGen Evidence Repository.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
SERPINC1	NM_000488.4	c.1154-14G>A		intron_variant		ENST00000367698.4	NP_000479.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
SERPINC1	ENST00000367698.4	c.1154-14G>A		intron_variant		1	NM_000488.4	ENSP00000356671.3

Frequencies

GnomAD3 genomes Cov.: 31

GnomAD4 exome AF: 6.85e-7 AC: 1 AN: 1458860 Hom.: 0 Cov.: 29 AF XY: 0.00 AC XY: 0 AN XY: 726020

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: 9.01e-7

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 31

Bravo AF: 0.00000378

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:3

Revision: reviewed by expert panel

Submissions by phenotype

Hereditary antithrombin deficiency Pathogenic:3

Likely pathogenic, criteria provided, single submitter	research	NIHR Bioresource Rare Diseases, University of Cambridge	Feb 01, 2019	- -
Pathogenic, criteria provided, single submitter	clinical testing	Labcorp Genetics (formerly Invitae), Labcorp	Aug 12, 2021	ClinVar contains an entry for this variant (Variation ID: 410384). This variant is also known as 9788G>A. This variant has been observed in individuals with antithrombin III deficiency (PMID: 7949130, 7981186, 8217824, 15164384, 23358206, 29662868, 30046692). It has also been observed to segregate with disease in related individuals. This variant is not present in population databases (ExAC no frequency). This sequence change falls in intron 5 of the SERPINC1 gene. It does not directly change the encoded amino acid sequence of the SERPINC1 protein. Studies have shown that this variant alters mRNA splicing and is expected to lead to the loss of protein expression (PMID: 7949130, 7981186). For these reasons, this variant has been classified as Pathogenic. -
Pathogenic, reviewed by expert panel	curation	Clingen Thrombosis Variant Curation Expert Panel, ClinGen	Sep 21, 2023	The NM_000488.3(SERPINC1):c.1154-14G>A variant is completely absent from gnomAD v2.1.1 and v3.1, meeting criteria for PM2_supporting. More than 20 probands across publications and internal laboratory data meet AT deficiency phenotype criteria and therefore, PS4_Very Strong is applied. 6 segregations across 4 families are counted in the literature (PMIDs: 7981186, 15164384, 7949130, 32686144), so PP1_Moderate is applied. SpliceAI predicts a cryptic acceptor splice site at -2bp with a score of 0.5. At least 2 publications (PMID: 7949130, PMID: 30046692) show experimental evidence of alternative splicing in patients due to the variant and therefore, PP3 is applied. The splicing aberration results in addition of 12bp of intron 4 into exon 5 of SERPINC1, increasing the protein length by 4 amino acids. This region is noted to be important for the folding and polymerization of the protein. Therefore, PM4 is applied. In summary, this variant meets criteria to be classified as pathogenic. ACMG/AMP criteria applied, as specified by the Thrombosis Variant Curation Expert Panel for SERPINC1: PS4_Very Strong, PM4, PP1_Moderate, PP3, PM2_Supporting. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.81
CADD	Benign	22
DANN	Benign	0.50

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.50		Details are displayed if max score is > 0.2
DS_AG_spliceai		0.50		Position offset: -2
DS_AL_spliceai		0.29		Position offset: -14

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

Publications

LitVar

Other links and lift over

dbSNP: rs542881762; hg19: chr1-173876666;