NM_054012.4:c.970G>T

Variant names:

• chr9-130489464-G-T
• rs121908639
• NM_054012.4:c.970G>T

Variant summary

Our verdict is Likely pathogenic. The variant received 9 ACMG points: 9P and 0B. PM2 PM5 PP2 PP3_Strong

The NM_054012.4(ASS1):​c.970G>T​(p.Gly324Cys) variant causes a missense, splice region change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000137 in 1,461,824 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. 16/26 in silico tools predict a damaging outcome for this variant. 3/3 splice prediction tools predicting alterations to normal splicing. No clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar. Another variant affecting the same amino acid position, but resulting in a different missense (i.e. G324V) has been classified as Likely pathogenic.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000014 (0 hom.)
• Consequence: ASS1 NM_054012.4 missense, splice_region
• Scores: Splicing: ADA: 1.000
• Clinical Significance: Not reported in ClinVar
• Conservation: PhyloP100: 9.28
• Publications: 32 publications found

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

ACMG classification

Our verdict: Likely_pathogenic. The variant received 9 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chr9-130494867-G-T is described in ClinVar as Pathogenic/Likely_pathogenic. ClinVar VariationId is 458676.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.
• PP2: Missense variant in the gene, where a lot of missense mutations are associated with disease in ClinVar. The gene has 49 curated pathogenic missense variants (we use a threshold of 10). The gene has 4 curated benign missense variants. Gene score misZ: 0.75759 (below the threshold of 3.09). Trascript score misZ: 1.8061 (below the threshold of 3.09). GenCC associations: The gene is linked to citrullinemia type I, adult-onset citrullinemia type I, acute neonatal citrullinemia type I.
• PP3: Splicing predictors support a deleterious effect. Scorers claiming Pathogenic: dbscSNV1_ADA, dbscSNV1_RF, max_spliceai. No scorers claiming Uncertain. No scorers claiming Benign.

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_054012.4. You can select a different transcript below to see updated ACMG assignments.

RefSeq Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	ASS1	NM_054012.4	MANE Select	c.970G>T	p.Gly324Cys	missense splice_region	Exon 12 of 15	NP_446464.1
	ASS1	NM_000050.4		c.970G>T	p.Gly324Cys	missense splice_region	Exon 13 of 16	NP_000041.2

Ensembl Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	ASS1	ENST00000352480.10	TSL:1 MANE Select	c.970G>T	p.Gly324Cys	missense splice_region	Exon 12 of 15	ENSP00000253004.6
	ASS1	ENST00000372393.7	TSL:5	c.970G>T	p.Gly324Cys	missense splice_region	Exon 13 of 16	ENSP00000361469.2
	ASS1	ENST00000372394.5	TSL:2	c.970G>T	p.Gly324Cys	missense splice_region	Exon 13 of 16	ENSP00000361471.1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD2 exomes AF: 0.00000398 AC: 1 AN: 251184 AF XY: 0.00000736

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 FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00000880

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000137 AC: 2 AN: 1461824 Hom.: 0 Cov.: 33 AF XY: 0.00000138 AC XY: 1 AN XY: 727218

⚠️ The allele balance in gnomAD version 4 Exomes is significantly skewed from the expected value of 0.5.

African (AFR) AF: 0.00 AC: 0 AN: 33480

American (AMR) AF: 0.00 AC: 0 AN: 44722

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26136

East Asian (EAS) AF: 0.00 AC: 0 AN: 39698

South Asian (SAS) AF: 0.00 AC: 0 AN: 86258

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53384

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5768

European-Non Finnish (NFE) AF: 8.99e-7 AC: 1 AN: 1111984

Other (OTH) AF: 0.0000166 AC: 1 AN: 60394

⚠️ The allele balance in gnomAD4 Exomes is highly skewed from 0.5 (p-value = 0.00000000770867), which strongly suggests a high chance of mosaicism in these individuals.

GnomAD4 genome Cov.: 32

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.98
BayesDel_addAF	Pathogenic	0.58	D
BayesDel_noAF	Pathogenic	0.60
CADD	Pathogenic	34
DANN	Uncertain	1.0
DEOGEN2	Pathogenic	1.0	D
Eigen	Pathogenic	0.83
Eigen_PC	Uncertain	0.63
FATHMM_MKL	Uncertain	0.96	D
LIST_S2	Pathogenic	0.98	D
M_CAP	Pathogenic	0.74	D
MetaRNN	Pathogenic	1.0	D
MetaSVM	Pathogenic	0.88	D
MutationAssessor	Pathogenic	4.4	H
PhyloP100		9.3
PrimateAI	Pathogenic	0.87	D
PROVEAN	Pathogenic	-8.8	D
REVEL	Pathogenic	0.96
Sift	Pathogenic	0.0	D
Sift4G	Pathogenic	0.0	D
Polyphen		1.0	D
Vest4		0.97
MutPred		0.96		Gain of helix (P = 0.132)
MVP		0.99
MPC		0.96
ClinPred		1.0	D
GERP RS		4.5
Varity_R		0.97
gMVP		0.95
Mutation Taster		=12/88	disease causing

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	1.0
SpliceAI score (max)		0.57		Details are displayed if max score is > 0.2
DS_DL_spliceai		0.57		Position offset: 0

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

Other links and lift over

dbSNP: rs121908639; hg19: chr9-133364851;