rs121908638

Positions:

Variant summary

Our verdict is Pathogenic. Variant got 16 ACMG points: 16P and 0B. PM1PM2PM5PP3_ModeratePP5_Very_Strong

The ENST00000352480.10(ASS1):c.539G>A(p.Ser180Asn) variant causes a missense change. The variant allele was found at a frequency of 0.0000849 in 1,614,008 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 Likely pathogenic (★★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. S180I) has been classified as Likely pathogenic.

Frequency

Genomes: 𝑓 0.000013 ( 0 hom., cov: 33)

Exomes 𝑓: 0.000092 ( 0 hom. )

Consequence

ASS1
ENST00000352480.10 missense

Scores

Clinical Significance

Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:9

Conservation

PhyloP100: 7.15

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 links:

Genome browser will be placed here

ACMG classification

Classification made for transcript

Verdict is Pathogenic. Variant got 16 ACMG points.

PM1

In a hotspot region, there are 3 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 0 benign, 6 uncertain in ENST00000352480.10

PM2

Very rare variant in population databases, with high coverage;

PM5

Other missense variant is known to change same aminoacid residue: Variant chr9-130470877-G-T is described in ClinVar as [Likely_pathogenic]. Clinvar id is 458674.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

PP3

MetaRNN computational evidence supports a deleterious effect, 0.91

PP5

Variant 9-130470877-G-A is Pathogenic according to our data. Variant chr9-130470877-G-A is described in ClinVar as [Likely_pathogenic]. Clinvar id is 6326.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars. Variant chr9-130470877-G-A is described in Lovd as [Pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
ASS1	NM_054012.4 linkuse as main transcript	c.539G>A	p.Ser180Asn	missense_variant	7/15	ENST00000352480.10	NP_446464.1
ASS1	NM_000050.4 linkuse as main transcript	c.539G>A	p.Ser180Asn	missense_variant	8/16		NP_000041.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
ASS1	ENST00000352480.10 linkuse as main transcript	c.539G>A	p.Ser180Asn	missense_variant	7/15	1	NM_054012.4	ENSP00000253004	P1

Frequencies

GnomAD3 genomes

AF:

0.0000131

AC:

AN:

152192

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.00

Gnomad AMI

AF:

0.00

Gnomad AMR

AF:

0.00

Gnomad ASJ

AF:

0.00

Gnomad EAS

AF:

0.00

Gnomad SAS

AF:

0.00

Gnomad FIN

AF:

0.00

Gnomad MID

AF:

0.00

Gnomad NFE

AF:

0.0000294

Gnomad OTH

AF:

0.00

GnomAD3 exomes

AF:

0.0000398

AC:

AN:

251466

Hom.:

AF XY:

0.0000441

AC XY:

AN XY:

135906

show subpopulations

Gnomad AFR exome

AF:

0.00

Gnomad AMR exome

AF:

0.00

Gnomad ASJ exome

AF:

0.00

Gnomad EAS exome

AF:

0.00

Gnomad SAS exome

AF:

0.00

Gnomad FIN exome

AF:

0.00

Gnomad NFE exome

AF:

0.0000879

Gnomad OTH exome

AF:

0.00

GnomAD4 exome

AF:

0.0000924

AC:

135

AN:

1461816

Hom.:

Cov.:

AF XY:

0.0000880

AC XY:

AN XY:

727196

show subpopulations

Gnomad4 AFR exome

AF:

0.0000299

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:

0.000109

Gnomad4 OTH exome

AF:

0.000215

GnomAD4 genome

AF:

0.0000131

AC:

AN:

152192

Hom.:

Cov.:

AF XY:

0.0000269

AC XY:

AN XY:

74354

show subpopulations

Gnomad4 AFR

AF:

0.00

Gnomad4 AMR

AF:

0.00

Gnomad4 ASJ

AF:

0.00

Gnomad4 EAS

AF:

0.00

Gnomad4 SAS

AF:

0.00

Gnomad4 FIN

AF:

0.00

Gnomad4 NFE

AF:

0.0000294

Gnomad4 OTH

AF:

0.00

Alfa

AF:

0.000135

Hom.:

Bravo

AF:

0.0000264

ExAC

AF:

0.00000824

AC:

EpiCase

AF:

0.00

EpiControl

AF:

0.000119

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:9

Revision: criteria provided, multiple submitters, no conflicts

LINK: link

Submissions by phenotype

Citrullinemia type I

Pathogenic:7

Pathogenic, criteria provided, single submitter	clinical testing	Women's Health and Genetics/Laboratory Corporation of America, LabCorp	Mar 10, 2017	Variant summary: The ASS1 c.539G>A (p.Ser180Asn) variant involves the alteration of a conserved nucleotide. 5/5 in silico tools predict a damaging outcome for this variant. This variant was found in 1/121356 control chromosomes at a frequency of 0.0000082, which does not exceed the estimated maximal expected allele frequency of a pathogenic ASS1 variant (0.0040825). The variant has been reported in affected individuals in the literature, and was shown in experimental studies to result in ~10% enzyme activity (Diez-Fernandez_2016). Additionally, an internal specimen carrying this variant was specified to have affected cousin who was homozygous for the mutation. Multiple clinical diagnostic laboratories/reputable databases classified this variant as pathogenic. Taken together, this variant is classified as pathogenic. -
Likely pathogenic, criteria provided, single submitter	curation	SIB Swiss Institute of Bioinformatics	May 31, 2018	This variant is interpreted as a Likely Pathogenic, for Citrullinemia 1, in Autosomal Recessive manner. The following ACMG Tag(s) were applied: PP3 => Multiple lines of computational evidence support a deleterious effect on the gene or gene product. PM2 => Absent from controls (or at extremely low frequency if recessive) in Exome Sequencing Project, 1000 Genomes Project, or Exome Aggregation Consortium. PS3 => Well-established functional studies show a deleterious effect (PMID:27287393). -
Pathogenic, criteria provided, single submitter	clinical testing	Revvity Omics, Revvity	Jun 20, 2023	- -
Pathogenic, criteria provided, single submitter	clinical testing	Fulgent Genetics, Fulgent Genetics	Feb 25, 2022	- -
Likely pathogenic, criteria provided, single submitter	clinical testing	Illumina Laboratory Services, Illumina	Apr 28, 2017	The ASS1 c.539G>A (p.Ser180Asn) variant has been reported in a total of three individuals with citrullinemia, all in a compound heterozygous state (Kobayashi et al. 1990; Dimmock et al. 2008; Rhee et al. 2013). Control data are not available for this variant, which is reported at a frequency of 0.00002 in the European (non-Finnish) population of the Exome Aggregation Consortium, though this is based on one allele in a region of good sequencing coverage. Functional studies in E. coli demonstrated the p.Ser180Asn variant had decreased binding affinity for aspartate and citrulline. The activity of the p.Ser180Asn variant increased to approximately 10% of wild type when exposed to large doses of aspartate (Diez-Fernandez et al. 2016). Based on the evidence, the p.Ser180Asn variant is classified as likely pathogenic for citrullinemia. This variant was observed by ICSL as part of a predisposition screen in an ostensibly healthy population. -
Pathogenic, no assertion criteria provided	literature only	OMIM	Apr 04, 2013	- -
Pathogenic, criteria provided, single submitter	clinical testing	Baylor Genetics	Mar 02, 2024	- -

Citrullinemia

Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Jan 18, 2024

This sequence change replaces serine, which is neutral and polar, with asparagine, which is neutral and polar, at codon 180 of the ASS1 protein (p.Ser180Asn). This variant is present in population databases (rs121908638, gnomAD 0.008%). This missense change has been observed in individual(s) with citrullinemia type I, including symptoms of hyperammonemia and markedly elevated plasma citrulline (PMID: 2358466, 18925679, 24765495; Invitae). ClinVar contains an entry for this variant (Variation ID: 6326). 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 ASS1 protein function with a positive predictive value of 80%. For these reasons, this variant has been classified as Pathogenic. -

not provided

Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

GeneDx

Jan 18, 2023

Published functional studies found this variant is associated with significantly decreased enzyme activity and thermal stability (Diez-Fernandez C et al., 2016); Not observed at a significant frequency in large population cohorts (gnomAD); In silico analysis supports that this missense variant has a deleterious effect on protein structure/function; This variant is associated with the following publications: (PMID: 18323623, 31469252, 27287393, 2358466) -

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Pathogenic

0.99

BayesDel_addAF

Pathogenic

0.16

BayesDel_noAF

Pathogenic

0.19

CADD

Pathogenic

DANN

Uncertain

0.98

DEOGEN2

Pathogenic

0.99

D;D;D;.;.

Eigen

Uncertain

0.67

Eigen_PC

Uncertain

0.47

FATHMM_MKL

Uncertain

0.93

LIST_S2

Benign

0.77

.;.;T;T;T

M_CAP

Pathogenic

0.63

MetaRNN

Pathogenic

0.91

D;D;D;D;D

MetaSVM

Pathogenic

1.0

MutationAssessor

Pathogenic

4.3

H;H;H;.;.

MutationTaster

Benign

1.0

A;A;A;A

PrimateAI

Uncertain

0.70

PROVEAN

Uncertain

-2.8

D;D;D;D;D

REVEL

Pathogenic

0.88

Sift

Pathogenic

0.0

D;D;D;D;D

Sift4G

Pathogenic

0.0

D;D;D;D;D

Polyphen

0.99

D;D;D;.;.

Vest4

0.95

MVP

0.98

MPC

0.42

ClinPred

0.93

GERP RS

3.3

Varity_R

0.93

gMVP

0.97

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

Below is the list of publications found by LitVar. It may be empty.

Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

ACMG classification

Transcripts

RefSeq

Ensembl

Frequencies

ClinVar

Submissions by phenotype

Computational scores

Splicing

Publications

LitVar

Other links and lift over