6-131582619-A-T

Variant names:

• chr6-131582619-A-T
• rs1554251045
• NM_000045.4:c.466-2A>T

Variant summary

Our verdict is Pathogenic. The variant received 10 ACMG points: 10P and 0B. PVS1 PM2

The NM_000045.4(ARG1):​c.466-2A>T 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. No clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar.

• Frequency: Genomes: not found (cov: 32)
• Consequence: ARG1 NM_000045.4 splice_acceptor, intron
• Scores: Splicing: ADA: 1.000
• Clinical Significance: Not reported in ClinVar
• Conservation: PhyloP100: 9.02
• Publications: 0 publications found

Genes affected

ARG1 (HGNC:663): (arginase 1) Arginase catalyzes the hydrolysis of arginine to ornithine and urea. At least two isoforms of mammalian arginase exist (types I and II) which differ in their tissue distribution, subcellular localization, immunologic crossreactivity and physiologic function. The type I isoform encoded by this gene, is a cytosolic enzyme and expressed predominantly in the liver as a component of the urea cycle. Inherited deficiency of this enzyme results in argininemia, an autosomal recessive disorder characterized by hyperammonemia. Two transcript variants encoding different isoforms have been found for this gene. [provided by RefSeq, Sep 2011]

MED23 (HGNC:2372): (mediator complex subunit 23) The activation of gene transcription is a multistep process that is triggered by factors that recognize transcriptional enhancer sites in DNA. These factors work with co-activators to direct transcriptional initiation by the RNA polymerase II apparatus. The protein encoded by this gene is a subunit of the CRSP (cofactor required for SP1 activation) complex, which, along with TFIID, is required for efficient activation by SP1. This protein is also a component of other multisubunit complexes e.g. thyroid hormone receptor-(TR-) associated proteins which interact with TR and facilitate TR function on DNA templates in conjunction with initiation factors and cofactors. This protein also acts as a metastasis suppressor. Several alternatively spliced transcript variants encoding different isoforms have been described for this gene. [provided by RefSeq, Jul 2012]

MED23 Gene-Disease associations (from GenCC):

• intellectual disability, autosomal recessive 18

  Inheritance: AR Classification: STRONG, MODERATE, LIMITED Submitted by: Ambry Genetics, Labcorp Genetics (formerly Invitae), G2P
• syndromic intellectual disability

  Inheritance: AR Classification: MODERATE Submitted by: ClinGen
• autosomal recessive non-syndromic intellectual disability

  Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet

ACMG classification

Our verdict: Pathogenic. The variant received 10 ACMG points.

• PVS1: Splicing +-2 bp (donor or acceptor) variant, LoF is a know mechanism of disease, Cryptic splice site detected, with MaxEntScore 3.7, offset of 16, new splice context is: tttgattcccgatgtgccAGgat. Cryptic site results in frameshift change. If cryptic site found is not functional and variant results in exon loss, it results in frameshift change.
• PM2: Very rare variant in population databases, with high coverage

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_000045.4. 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
	ARG1	NM_000045.4	MANE Select	c.466-2A>T		splice_acceptor intron	N/A	NP_000036.2
	MED23	NM_015979.4		c.4095+5090T>A		intron	N/A	NP_057063.2
	MED23	NM_001270521.2		c.4077+5090T>A		intron	N/A	NP_001257450.1

Ensembl Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	ARG1	ENST00000368087.8	TSL:1 MANE Select	c.466-2A>T		splice_acceptor intron	N/A	ENSP00000357066.3
	MED23	ENST00000354577.8	TSL:1	c.4095+5090T>A		intron	N/A	ENSP00000346588.4
	ARG1	ENST00000356962.2	TSL:1	c.490-2A>T		splice_acceptor intron	N/A	ENSP00000349446.2

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 30

GnomAD4 genome Cov.: 32

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.63	D
BayesDel_noAF	Uncertain	-0.060
CADD	Pathogenic	33
DANN	Benign	0.97
Eigen	Pathogenic	0.89
Eigen_PC	Pathogenic	0.67
FATHMM_MKL	Pathogenic	1.0	D
PhyloP100		9.0
GERP RS		4.6
Mutation Taster		=9/91	disease causing

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	0.91
SpliceAI score (max)		0.83		Details are displayed if max score is > 0.2
DS_AG_spliceai		0.65		Position offset: -49
DS_AL_spliceai		0.83		Position offset: 2

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

Other links and lift over

dbSNP: rs1554251045; hg19: chr6-131903759;