3-148994189-G-T

Position:

• chr3-148994189-G-T

Variant summary

Our verdict is Uncertain significance. Variant got 4 ACMG points: 4P and 0B. PM2 PP3_Moderate

The NM_004130.4(GYG1):​c.55G>T​(p.Ala19Ser) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.000000684 in 1,461,612 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 Uncertain significance (★★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. A19V) has been classified as Uncertain significance.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 6.8e-7 (0 hom.)
• Consequence: GYG1 NM_004130.4 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:2
• Conservation: PhyloP100: 9.59

Genes affected

GYG1 (HGNC:4699): (glycogenin 1) This gene encodes a member of the glycogenin family. Glycogenin is a glycosyltransferase that catalyzes the formation of a short glucose polymer from uridine diphosphate glucose in an autoglucosylation reaction. This reaction is followed by elongation and branching of the polymer, catalyzed by glycogen synthase and branching enzyme, to form glycogen. This gene is expressed in muscle and other tissues. Mutations in this gene result in glycogen storage disease XV. This gene has pseudogenes on chromosomes 1, 8 and 13 respectively. Alternatively spliced transcript variants encoding different isoforms have been identified.[provided by RefSeq, Sep 2010]

ACMG classification

Verdict is Uncertain_significance. Variant got 4 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.858

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
GYG1	NM_004130.4	c.55G>T	p.Ala19Ser	missense_variant	2/8	ENST00000345003.9
GYG1	NM_001184720.2	c.55G>T	p.Ala19Ser	missense_variant	2/7
GYG1	NM_001184721.2	c.55G>T	p.Ala19Ser	missense_variant	2/6
GYG1	XM_017006275.2	c.-34-2113G>T		intron_variant

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
GYG1	ENST00000345003.9	c.55G>T	p.Ala19Ser	missense_variant	2/8	1	NM_004130.4

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD3 exomes AF: 0.00000795 AC: 2 AN: 251464 Hom.: 0 AF XY: 0.00 AC XY: 0 AN XY: 135914

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 SAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.0000176

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 6.84e-7 AC: 1 AN: 1461612 Hom.: 0 Cov.: 32 AF XY: 0.00 AC XY: 0 AN XY: 727134

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.: 32

Alfa AF: 0.0000312 Hom.: 0

ESP6500AA AF: 0.00 AC: 0

ESP6500EA AF: 0.000116 AC: 1

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:2

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Inborn genetic diseases Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Ambry Genetics

Jul 09, 2021

The c.55G>T (p.A19S) alteration is located in exon 2 (coding exon 2) of the GYG1 gene. This alteration results from a G to T substitution at nucleotide position 55, causing the alanine (A) at amino acid position 19 to be replaced by a serine (S). Based on insufficient or conflicting evidence, the clinical significance of this alteration remains unclear. -

Glycogen storage disease XV;C4015452:Polyglucosan body myopathy type 2 Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Invitae

Jul 06, 2022

This sequence change replaces alanine, which is neutral and non-polar, with serine, which is neutral and polar, at codon 19 of the GYG1 protein (p.Ala19Ser). In summary, the available evidence is currently insufficient to determine the role of this variant in disease. Therefore, it has been classified as a Variant of Uncertain Significance. Algorithms developed to predict the effect of missense changes on protein structure and function are either unavailable or do not agree on the potential impact of this missense change (SIFT: "Deleterious"; PolyPhen-2: "Probably Damaging"; Align-GVGD: "Class C0"). ClinVar contains an entry for this variant (Variation ID: 1471209). This variant has not been reported in the literature in individuals affected with GYG1-related conditions. This variant is present in population databases (rs148954947, gnomAD 0.0009%). -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.19
BayesDel_addAF	Pathogenic	0.18	D
BayesDel_noAF	Uncertain	0.020
CADD	Pathogenic	28
DANN	Uncertain	1.0
DEOGEN2	Uncertain	0.79	D;.;.;.;.;D
Eigen	Pathogenic	1.0
Eigen_PC	Pathogenic	0.96
FATHMM_MKL	Pathogenic	0.98	D
LIST_S2	Uncertain	0.93	D;D;D;.;D;D
M_CAP	Uncertain	0.085	D
MetaRNN	Pathogenic	0.86	D;D;D;D;D;D
MetaSVM	Uncertain	0.24	D
MutationAssessor	Pathogenic	4.0	H;.;H;.;H;.
MutationTaster	Benign	1.0	D;D;D;D
PrimateAI	Uncertain	0.71	T
PROVEAN	Uncertain	-2.8	D;.;D;D;D;D
REVEL	Uncertain	0.59
Sift	Uncertain	0.0030	D;.;D;D;D;D
Sift4G	Uncertain	0.0050	D;D;D;D;D;D
Polyphen		1.0	D;D;D;D;.;.
Vest4		0.77
MVP		0.85
MPC		0.48
ClinPred		0.99	D
GERP RS		5.3
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.7
Varity_R		0.77
gMVP		0.66

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.020		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: rs148954947; hg19: chr3-148711976;