9-130466723-A-G

Variant names:

Variant summary

Our verdict is Pathogenic. The variant received 10 ACMG points: 10P and 0B. PVS1_ModeratePP5_Very_Strong

The NM_054012.4(ASS1):c.421-2A>G variant causes a splice acceptor, intron change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.0000109 in 1,461,626 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. 3/3 splice prediction tools predicting alterations to normal splicing. Variant has been reported in ClinVar as Pathogenic (★★).

Frequency

Genomes: not found (cov: 33)

Exomes 𝑓: 0.000011 ( 0 hom. )

Consequence

ASS1
NM_054012.4 splice_acceptor, intron

Scores

Splicing: ADA: 1.000

Clinical Significance

Pathogenic criteria provided, multiple submitters, no conflicts P:8O:1

Conservation

PhyloP100: 8.12

Publications

12 publications found

Variant links:

Genes affected

ASS1 (HGNC:758): (argininosuccinate synthase 1) The protein encoded by this gene catalyzes the penultimate step of the arginine biosynthetic pathway. There are approximately 10 to 14 copies of this gene including the pseudogenes scattered across the human genome, among which the one located on chromosome 9 appears to be the only functional gene for argininosuccinate synthetase. Mutations in the chromosome 9 copy of this gene cause citrullinemia. Two transcript variants encoding the same protein have been found for this gene. [provided by RefSeq, Aug 2012]

ASS1 Gene-Disease associations (from GenCC):

citrullinemia type I
Inheritance: AR Classification: DEFINITIVE, STRONG Submitted by: Labcorp Genetics (formerly Invitae), ClinGen, Myriad Women’s Health, G2P
acute neonatal citrullinemia type I
Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet
adult-onset citrullinemia type I
Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet

ASS1 links:

Genome browser will be placed here

ACMG classification

Classification was made for transcript

Our verdict: Pathogenic. The variant received 10 ACMG points.

PVS1

Splicing +-2 bp (donor or acceptor) variant, product NOT destroyed by NMD, known LOF gene, truncates exone, which is 0.06053269 fraction of the gene. No cryptic splice site detected. Exon removal is inframe change.

PP5

Variant 9-130466723-A-G is Pathogenic according to our data. Variant chr9-130466723-A-G is described in ClinVar as Pathogenic. ClinVar VariationId is 198386.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
ASS1	NM_054012.4 link	c.421-2A>G		splice_acceptor_variant, intron_variant	Intron 5 of 14	ENST00000352480.10	NP_446464.1
ASS1	NM_000050.4 link	c.421-2A>G		splice_acceptor_variant, intron_variant	Intron 6 of 15		NP_000041.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
ASS1	ENST00000352480.10 link	c.421-2A>G		splice_acceptor_variant, intron_variant	Intron 5 of 14	1	NM_054012.4	ENSP00000253004.6

Frequencies

GnomAD3 genomes

Cov.:

GnomAD2 exomes

AF:

0.0000119

AC:

AN:

251174

AF XY:

0.00000736

show subpopulations

Gnomad AFR exome

AF:

0.00

Gnomad AMR exome

AF:

0.00

Gnomad ASJ exome

AF:

0.00

Gnomad EAS exome

AF:

0.000163

Gnomad FIN exome

AF:

0.00

Gnomad NFE exome

AF:

0.00

Gnomad OTH exome

AF:

0.00

GnomAD4 exome

AF:

0.0000109

AC:

AN:

1461626

Hom.:

Cov.:

AF XY:

0.0000124

AC XY:

AN XY:

727138

show subpopulations

African (AFR)

AF:

0.00

AC:

AN:

33480

American (AMR)

AF:

0.00

AC:

AN:

44722

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

26132

East Asian (EAS)

AF:

0.000378

AC:

AN:

39700

South Asian (SAS)

AF:

0.00

AC:

AN:

86256

European-Finnish (FIN)

AF:

0.00

AC:

AN:

53240

Middle Eastern (MID)

AF:

0.00

AC:

AN:

5768

European-Non Finnish (NFE)

AF:

8.99e-7

AC:

AN:

1111936

Other (OTH)

AF:

0.00

AC:

AN:

60392

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.466

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Age Distribution

Exome Het

Variant carriers

<30

30-35

35-40

40-45

45-50

50-55

55-60

60-65

65-70

70-75

75-80

>80

Age

GnomAD4 genome

Cov.:

Alfa

AF:

0.0000841

Hom.:

ExAC

AF:

0.0000247

AC:

Asia WGS

AF:

0.000289

AC:

AN:

3478

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:8Other:1

Revision: criteria provided, multiple submitters, no conflicts

LINK: link

Submissions by phenotype

Citrullinemia type I

Pathogenic:6Other:1

Aug 25, 2020

Natera, Inc.

Significance:Pathogenic

Review Status:no assertion criteria provided

Collection Method:clinical testing

Feb 17, 2020

Women's Health and Genetics/Laboratory Corporation of America, LabCorp

Significance:Pathogenic

Review Status:criteria provided, single submitter

Collection Method:clinical testing

Variant summary: ASS1 c.421-2A>G is located in a canonical splice-site and is predicted to affect mRNA splicing resulting in a significantly altered protein due to either exon skipping, shortening, or inclusion of intronic material. Several computational tools predict a significant impact on normal splicing: four predict the variant abolishes a 3' acceptor site. At least one publication reports experimental evidence demonstrating that this variant causes an in-frame skipping of exon 7 (Kobayashi_1994). The variant allele was found at a frequency of 1.2e-05 in 251174 control chromosomes, exclusively observed within the East Asian subpopulation (gnomAD). The variant, c.421-2A>G, is a common disease variant in Japan and Korea, and was reported in the literature in several homozygous and compound heterozygous individuals affected with Citrullinemia Type I (e.g. Kobayashi_1995, Lee_2013). These data indicate that the variant is very likely to be associated with disease. Publications also reported that the variant results in less than 2% of normal activity and the almost complete absence of the ASS1 protein in liver specimens of homozygous patients (Kobayashi_1995). Two clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar after 2014 without evidence for independent evaluation, and both of them classified the variant as pathogenic. Based on the evidence outlined above, the variant was classified as pathogenic.

Nov 11, 2019

Myriad Genetics, Inc.

Significance:Pathogenic

Review Status:criteria provided, single submitter

Collection Method:clinical testing

NM_000050.4(ASS1):c.421-2A>G is classified as pathogenic in the context of type 1 citrullinemia. Sources cited for classification include the following: PMID 23246278. Classification of NM_000050.4(ASS1):c.421-2A>G is based on the following criteria: The variant is located at a canonical splice site, is expected to disrupt gene function and is reported in individuals with the relevant phenotype. Please note: this variant was assessed in the context of healthy population screening.

Oct 01, 1995

OMIM

Significance:Pathogenic

Review Status:no assertion criteria provided

Collection Method:literature only

Oct 02, 2021

3billion

Significance:Pathogenic

Review Status:criteria provided, single submitter

Collection Method:clinical testing

Canonical splice site: predicted to alter splicing and result in a loss or disruption of normal protein function through nonsense-mediated decay (NMD) or protein truncation. Multiple pathogenic variants are reported downstream of the variant (PVS1_VS). It is observed at an extremely low frequency in the gnomAD v2.1.1 dataset (total allele frequency: 0.0000119, PM2). The variant has been reported multiple times as an established pathogenic variant (ClinVar ID: VCV000198386.5). Therefore, this variant is classified as pathogenic according to the recommendation of ACMG/AMP guideline.

GeneReviews

Significance:not provided

Review Status:no classification provided

Collection Method:literature only

Jan 10, 2024

Baylor Genetics

Significance:Pathogenic

Review Status:criteria provided, single submitter

Collection Method:clinical testing

Citrullinemia

Pathogenic:1

Feb 26, 2023

Labcorp Genetics (formerly Invitae), Labcorp

Significance:Pathogenic

Review Status:criteria provided, single submitter

Collection Method:clinical testing

For these reasons, this variant has been classified as Pathogenic. Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant may disrupt the consensus splice site. ClinVar contains an entry for this variant (Variation ID: 198386). This variant is also known as IVS-6 -2 (a transition of A to G) or IVS6-2A>G. Disruption of this splice site has been observed in individual(s) with citrullinemia (PMID: 7557970, 10987146). In at least one individual the data is consistent with being in trans (on the opposite chromosome) from a pathogenic variant. This variant is present in population databases (rs751930594, gnomAD 0.02%). This sequence change affects an acceptor splice site in intron 6 of the ASS1 gene. It is expected to disrupt RNA splicing. Variants that disrupt the donor or acceptor splice site typically lead to a loss of protein function (PMID: 16199547), and loss-of-function variants in ASS1 are known to be pathogenic (PMID: 18473344, 19006241).

not provided

Pathogenic:1

Jul 14, 2014

Eurofins Ntd Llc (ga)

Significance:Pathogenic

Review Status:criteria provided, single submitter

Collection Method:clinical testing

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

BayesDel_addAF

Pathogenic

0.41

BayesDel_noAF

Uncertain

-0.060

CADD

Pathogenic

(source)

DANN

Uncertain

0.99

DEOGEN2

Benign

0.0

.;.;.;.;.

Eigen

Pathogenic

0.95

Eigen_PC

Pathogenic

0.74

FATHMM_MKL

Pathogenic

0.98

LIST_S2

Benign

0.0

.;.;.;.;.

MetaRNN

Benign

0.0

.;.;.;.;.

MutationAssessor

Benign

0.0

.;.;.;.;.

PhyloP100

8.1

PROVEAN

Benign

0.0

.;.;.;.;.

REVEL

Benign

0.0

Sift

Pathogenic

0.0

.;.;.;.;.

Sift4G

Pathogenic

0.0

.;.;.;.;.

Vest4

0.0

GERP RS

4.8

Mutation Taster

=0/100

disease causing (ClinVar)

(source)

Splicing

Name

Calibrated prediction

Score

Prediction

dbscSNV1_ADA

Pathogenic

1.0

dbscSNV1_RF

Pathogenic

0.89

SpliceAI score (max)

0.99

Details are displayed if max score is > 0.2

DS_AG_spliceai

0.40

Position offset: 19

DS_AL_spliceai

0.99

Position offset: 2

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

Publications

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Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

Publications

ACMG classification

Transcripts

RefSeq

Ensembl

Frequencies

Age Distribution

ClinVar

Submissions by phenotype

Computational scores

Splicing

Publications

Other links and lift over