9-130464127-G-T

Position:

• chr9-130464127-G-T

Variant summary

Our verdict is Pathogenic. Variant got 18 ACMG points: 18P and 0B. PM1 PM2 PM5 PP3_Strong PP5_Very_Strong

The NM_054012.4(ASS1):​c.380G>T​(p.Arg127Leu) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.000000684 in 1,461,880 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. R127Q) has been classified as Pathogenic.

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 6.8e-7 (0 hom.)
• Consequence: ASS1 NM_054012.4 missense
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:3 U:1
• Conservation: PhyloP100: 8.34

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 18 ACMG points.

• PM1: In a helix (size 11) in uniprot entity ASSY_HUMAN there are 4 pathogenic changes around while only 0 benign (100%) 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 chr9-130464127-G-A is described in Lovd as [Pathogenic].
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.988
• PP5: Variant 9-130464127-G-T is Pathogenic according to our data. Variant chr9-130464127-G-T is described in ClinVar as [Likely_pathogenic]. Clinvar id is 550586.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
ASS1	NM_054012.4	c.380G>T	p.Arg127Leu	missense_variant	5/15	ENST00000352480.10	NP_446464.1
ASS1	NM_000050.4	c.380G>T	p.Arg127Leu	missense_variant	6/16		NP_000041.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
ASS1	ENST00000352480.10	c.380G>T	p.Arg127Leu	missense_variant	5/15	1	NM_054012.4	ENSP00000253004	P1

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome AF: 6.84e-7 AC: 1 AN: 1461880 Hom.: 0 Cov.: 32 AF XY: 0.00 AC XY: 0 AN XY: 727242

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: 8.99e-7

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 33

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:3 Uncertain:1

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Citrullinemia type I Pathogenic:2 Uncertain:1

Uncertain significance, flagged submission	clinical testing	Counsyl	Feb 07, 2017	- -
Pathogenic, criteria provided, single submitter	clinical testing	Centogene AG - the Rare Disease Company	-	- -
Pathogenic, no assertion criteria provided	clinical testing	Biochemical Molecular Genetic Laboratory, King Abdulaziz Medical City	Aug 25, 2019	- -

Citrullinemia Pathogenic:1

Likely pathogenic, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Apr 25, 2023

This sequence change replaces arginine, which is basic and polar, with leucine, which is neutral and non-polar, at codon 127 of the ASS1 protein (p.Arg127Leu). 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. This variant disrupts the p.Arg127 amino acid residue in ASS1. Other variant(s) that disrupt this residue have been determined to be pathogenic (PMID: 14680976, 23099195, 28111830, 31208364). This suggests that this residue is clinically significant, and that variants that disrupt this residue are likely to be disease-causing. Experimental studies have shown that this missense change affects ASS1 function (PMID: 27287393). 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. ClinVar contains an entry for this variant (Variation ID: 550586). This missense change has been observed in individuals with Citrullinemia (PMID: 24889030, 32860008). This variant is not present in population databases (gnomAD no frequency). -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.98
BayesDel_addAF	Pathogenic	0.58	D
BayesDel_noAF	Pathogenic	0.60
CADD	Pathogenic	33
DANN	Uncertain	1.0
DEOGEN2	Pathogenic	1.0	D;D;D;.
Eigen	Pathogenic	1.0
Eigen_PC	Pathogenic	0.86
FATHMM_MKL	Uncertain	0.97	D
LIST_S2	Pathogenic	0.99	.;.;D;D
M_CAP	Pathogenic	0.57	D
MetaRNN	Pathogenic	0.99	D;D;D;D
MetaSVM	Pathogenic	0.95	D
MutationAssessor	Pathogenic	4.4	H;H;H;.
MutationTaster	Benign	1.0	D;D;D;D
PrimateAI	Uncertain	0.64	T
PROVEAN	Pathogenic	-6.7	D;D;D;D
REVEL	Pathogenic	0.99
Sift	Pathogenic	0.0	D;D;D;D
Sift4G	Pathogenic	0.0010	D;D;D;D
Polyphen		1.0	D;D;D;.
Vest4		0.95
MutPred		0.93		Gain of stability (P = 0.0076);Gain of stability (P = 0.0076);Gain of stability (P = 0.0076);Gain of stability (P = 0.0076);
MVP		0.98
MPC		1.0
ClinPred		1.0	D
GERP RS		4.5
Varity_R		0.98
gMVP		0.95

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.070		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: rs201623252; hg19: chr9-133339514; COSMIC: COSV61690315; COSMIC: COSV61690315;