rs1554725043

Positions:

• chr9-130494905-T-G

Variant summary

Our verdict is Pathogenic. Variant got 10 ACMG points: 10P and 0B. PM1 PM2 PM5 PP3_Strong

The NM_054012.4(ASS1):​c.1009T>G​(p.Cys337Gly) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.000000684 in 1,461,182 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 Uncertain significance (★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. C337R) has been classified as Likely pathogenic.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 6.8e-7 (0 hom.)
• Consequence: ASS1 NM_054012.4 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 7.43

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]

ACMG classification

Verdict is Pathogenic. Variant got 10 ACMG points.

• PM1: In a hotspot region, there are 2 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 1 benign, 3 uncertain in NM_054012.4
• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chrnull-null-null-null is described in UniProt as null.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.983

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
ASS1	NM_054012.4	c.1009T>G	p.Cys337Gly	missense_variant	13/15	ENST00000352480.10
ASS1	NM_000050.4	c.1009T>G	p.Cys337Gly	missense_variant	14/16

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
ASS1	ENST00000352480.10	c.1009T>G	p.Cys337Gly	missense_variant	13/15	1	NM_054012.4	P1
ASS1	ENST00000372393.7	c.1009T>G	p.Cys337Gly	missense_variant	14/16	5		P1
ASS1	ENST00000372394.5	c.1009T>G	p.Cys337Gly	missense_variant	14/16	2		P1
ASS1	ENST00000372386.6	n.280T>G		non_coding_transcript_exon_variant	4/6	3

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 6.84e-7 AC: 1 AN: 1461182 Hom.: 0 Cov.: 31 AF XY: 0.00000138 AC XY: 1 AN XY: 726914

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.: 32

Bravo AF: 0.00000756

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Citrullinemia Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Sep 02, 2021

This sequence change replaces cysteine with glycine at codon 337 of the ASS1 protein (p.Cys337Gly). The cysteine residue is moderately conserved and there is a large physicochemical difference between cysteine and glycine. This variant is not present in population databases (ExAC no frequency). This variant has not been reported in the literature in individuals affected with ASS1-related conditions. Algorithms developed to predict the effect of missense changes on protein structure and function are either unavailable or do not agree on the potential impact of this missense change (SIFT: "Tolerated"; PolyPhen-2: "Probably Damaging"; Align-GVGD: "Class C0"). In summary, the available evidence is currently insufficient to determine the role of this variant in disease. Therefore, it has been classified as a Variant of Uncertain Significance. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Uncertain	0.46
BayesDel_addAF	Pathogenic	0.52	D
BayesDel_noAF	Pathogenic	0.50
CADD	Pathogenic	28
DANN	Uncertain	0.98
DEOGEN2	Pathogenic	0.97	D;D;D
Eigen	Uncertain	0.65
Eigen_PC	Uncertain	0.62
FATHMM_MKL	Uncertain	0.94	D
LIST_S2	Uncertain	0.90	.;.;D
M_CAP	Pathogenic	0.78	D
MetaRNN	Pathogenic	0.98	D;D;D
MetaSVM	Pathogenic	1.1	D
MutationAssessor	Uncertain	2.4	M;M;M
MutationTaster	Benign	1.0	D;D;D;D
PrimateAI	Uncertain	0.73	T
PROVEAN	Pathogenic	-6.5	D;D;D
REVEL	Pathogenic	0.95
Sift	Benign	0.041	D;D;D
Sift4G	Benign	0.14	T;T;T
Polyphen		0.66	P;P;P
Vest4		0.94
MutPred		0.80		Gain of disorder (P = 0.0125);Gain of disorder (P = 0.0125);Gain of disorder (P = 0.0125);
MVP		0.99
MPC		0.97
ClinPred		0.99	D
GERP RS		4.8
Varity_R		0.93
gMVP		0.84

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: rs1554725043; hg19: chr9-133370292;