NM_054012.4:c.421-2A>C

Variant names:

• chr9-130466723-A-C
• rs751930594
• NM_054012.4:c.421-2A>C

Variant summary

Our verdict is Uncertain significance. The variant received 5 ACMG points: 5P and 0B. PVS1_Moderate PM2 PP5

The NM_054012.4(ASS1):​c.421-2A>C variant causes a splice acceptor, intron change involving the alteration of a conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. 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 Likely pathogenic (no stars).

• Frequency: Genomes: not found (cov: 33)
• Consequence: ASS1 NM_054012.4 splice_acceptor, intron
• Scores: Splicing: ADA: 1.000
• Clinical Significance: Likely pathogenic no assertion criteria provided P:1
• Conservation: PhyloP100: 8.12
• Publications: 12 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, G2P, Myriad Women’s Health
• 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: Uncertain_significance. The variant received 5 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.
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 9-130466723-A-C is Pathogenic according to our data. Variant chr9-130466723-A-C is described in ClinVar as Likely_pathogenic. ClinVar VariationId is 813407.Status of the report is no_assertion_criteria_provided, 0 stars.

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

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	ASS1	NM_054012.4	MANE Select	c.421-2A>C		splice_acceptor intron	N/A	NP_446464.1	Q5T6L4
	ASS1	NM_000050.4		c.421-2A>C		splice_acceptor intron	N/A	NP_000041.2	P00966

Ensembl Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	ASS1	ENST00000352480.10	TSL:1 MANE Select	c.421-2A>C		splice_acceptor intron	N/A	ENSP00000253004.6	P00966
	ASS1	ENST00000852201.1		c.421-2A>C		splice_acceptor intron	N/A	ENSP00000522260.1
	ASS1	ENST00000852207.1		c.421-2A>C		splice_acceptor intron	N/A	ENSP00000522266.1

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome Cov.: 31

GnomAD4 genome Cov.: 33

ClinVar

ClinVar submissions

Significance: Likely pathogenic

Revision: no assertion criteria provided

Pathogenic	VUS	Benign	Condition
1	-	-	Citrullinemia type I (1)

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.60	D
BayesDel_noAF	Benign	-0.11
CADD	Pathogenic	33
DANN	Uncertain	0.99
Eigen	Pathogenic	0.95
Eigen_PC	Pathogenic	0.74
FATHMM_MKL	Pathogenic	0.98	D
PhyloP100		8.1
GERP RS		4.8
Mutation Taster		=0/100	disease causing (ClinVar)

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		0.54		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

Other links and lift over

dbSNP: rs751930594; hg19: chr9-133342110;