12-21563227-C-G

Variant names:

• chr12-21563227-C-G
• rs587776831
• NM_021957.4:c.941+1G>C

Variant summary

Our verdict is Pathogenic. The variant received 12 ACMG points: 12P and 0B. PVS1 PM2 PP5_Moderate

The NM_021957.4(GYS2):​c.941+1G>C variant causes a splice donor, 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 Pathogenic (★).

• Frequency: Genomes: not found (cov: 32)
• Consequence: GYS2 NM_021957.4 splice_donor, intron
• Scores: Splicing: ADA: 1.000
• Clinical Significance: Pathogenic criteria provided, single submitter P:2
• Conservation: PhyloP100: 7.88
• Publications: 1 publications found

Genes affected

GYS2 (HGNC:4707): (glycogen synthase 2) The protein encoded by this gene, liver glycogen synthase, catalyzes the rate-limiting step in the synthesis of glycogen - the transfer of a glucose molecule from UDP-glucose to a terminal branch of the glycogen molecule. Mutations in this gene cause glycogen storage disease type 0 (GSD-0) - a rare type of early childhood fasting hypoglycemia with decreased liver glycogen content. [provided by RefSeq, Dec 2009]

GYS2 Gene-Disease associations (from GenCC):

• glycogen storage disorder due to hepatic glycogen synthase deficiency

  Inheritance: AR Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: Labcorp Genetics (formerly Invitae), Orphanet, ClinGen, Genomics England PanelApp

ENSG00000285854 (HGNC:):

ACMG classification

Our verdict: Pathogenic. The variant received 12 ACMG points.

• PVS1: Splicing +-2 bp (donor or acceptor) variant, LoF is a know mechanism of disease, Cryptic splice site detected, with MaxEntScore 3.3, offset of -13, new splice context is: gagGTcatt. 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
• PP5: Variant 12-21563227-C-G is Pathogenic according to our data. Variant chr12-21563227-C-G is described in ClinVar as Pathogenic. ClinVar VariationId is 16050.Status of the report is criteria_provided_single_submitter, 1 stars.

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_021957.4. 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
	GYS2	NM_021957.4	MANE Select	c.941+1G>C		splice_donor intron	N/A	NP_068776.2	P54840

Ensembl Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	GYS2	ENST00000261195.3	TSL:1 MANE Select	c.941+1G>C		splice_donor intron	N/A	ENSP00000261195.2	P54840
	ENSG00000285854	ENST00000647960.1		n.*943+1G>C		splice_donor intron	N/A	ENSP00000497202.1	A0A3B3IS95
	GYS2	ENST00000863011.1		c.1055+1G>C		splice_donor intron	N/A	ENSP00000533070.1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 25

GnomAD4 genome Cov.: 32

ClinVar

ClinVar submissions

Significance: Pathogenic

Revision: criteria provided, single submitter

Pathogenic	VUS	Benign	Condition
2	-	-	Glycogen storage disorder due to hepatic glycogen synthase deficiency (2)

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.63	D
BayesDel_noAF	Pathogenic	0.30
CADD	Pathogenic	34
DANN	Uncertain	1.0
Eigen	Pathogenic	1.2
Eigen_PC	Pathogenic	1.0
FATHMM_MKL	Uncertain	0.80	D
PhyloP100		7.9
GERP RS		5.1
Mutation Taster		=0/100	disease causing (ClinVar)

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	0.94
SpliceAI score (max)		0.98		Details are displayed if max score is > 0.2
DS_DG_spliceai		0.27		Position offset: 14
DS_DL_spliceai		0.98		Position offset: 1

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

Other links and lift over

dbSNP: rs587776831; hg19: chr12-21716161;