4-533822-A-G

Position:

• chr4-533822-A-G

Variant summary

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

The ENST00000453061.7(PIGG):​c.2576A>G​(p.Asn859Ser) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000274 in 1,461,812 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. N859D) has been classified as Uncertain significance.

• Frequency:
  • Genomes: not found (cov: 34)
  • Exomes 𝑓: 0.0000027 (0 hom.)
• Consequence: PIGG ENST00000453061.7 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:2
• Conservation: PhyloP100: 8.76

Genes affected

PIGG (HGNC:25985): (phosphatidylinositol glycan anchor biosynthesis class G (EMM blood group)) This gene encodes an enzyme involved in glycosylphosphatidylinositol-anchor biosynthesis. The encoded protein, which is localized to the endoplasmic reticulum, is involved in transferring ethanoloamine phosphate to mannose 2 of glycosylphosphatidylinositol species H7 to form species H8. Allelic variants of this gene have been associated with intellectual disability, hypotonia, and early-onset seizures. Alternative splicing results in multiple transcript variants. [provided by RefSeq, Sep 2016]

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, 0.843

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
PIGG	NM_001127178.3	c.2576A>G	p.Asn859Ser	missense_variant	12/13	ENST00000453061.7	NP_001120650.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
PIGG	ENST00000453061.7	c.2576A>G	p.Asn859Ser	missense_variant	12/13	1	NM_001127178.3	ENSP00000415203	P4

Frequencies

GnomAD3 genomes Cov.: 34

GnomAD3 exomes AF: 0.0000159 AC: 4 AN: 251334 Hom.: 0 AF XY: 0.0000147 AC XY: 2 AN XY: 135828

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.000116

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: 0.00

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000274 AC: 4 AN: 1461812 Hom.: 0 Cov.: 31 AF XY: 0.00000275 AC XY: 2 AN XY: 727214

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.0000894

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: 0.00

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 34

Bravo AF: 0.00000756

ExAC AF: 0.00000824 AC: 1

EpiCase AF: 0.0000545

EpiControl AF: 0.00

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:2

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Intellectual disability, autosomal recessive 53 Uncertain:2

Uncertain significance, criteria provided, single submitter	clinical testing	Baylor Genetics	Mar 22, 2018	This variant was determined to be of uncertain significance according to ACMG Guidelines, 2015 [PMID:25741868]. -
Uncertain significance, criteria provided, single submitter	clinical testing	Labcorp Genetics (formerly Invitae), Labcorp	Nov 22, 2022	This variant has not been reported in the literature in individuals affected with PIGG-related conditions. 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 sequence changes on RNA splicing suggest that this variant may create or strengthen a splice site. Advanced modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) performed at Invitae indicates that this missense variant is expected to disrupt PIGG protein function. ClinVar contains an entry for this variant (Variation ID: 570517). This variant is present in population databases (rs745840866, gnomAD 0.01%). This sequence change replaces asparagine, which is neutral and polar, with serine, which is neutral and polar, at codon 859 of the PIGG protein (p.Asn859Ser). -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.34
BayesDel_addAF	Benign	-0.14	T
BayesDel_noAF	Benign	-0.22
CADD	Pathogenic	32
DANN	Uncertain	1.0
DEOGEN2	Benign	0.18	.;T;T;.
Eigen	Pathogenic	0.91
Eigen_PC	Pathogenic	0.88
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Uncertain	0.96	D;D;D;D
M_CAP	Benign	0.015	T
MetaRNN	Pathogenic	0.84	D;D;D;D
MetaSVM	Benign	-0.58	T
MutationAssessor	Pathogenic	3.4	.;M;.;.
MutationTaster	Benign	1.0	D;D;D;D;D
PrimateAI	Uncertain	0.54	T
PROVEAN	Pathogenic	-4.8	D;D;D;D
REVEL	Uncertain	0.44
Sift	Pathogenic	0.0	D;D;D;D
Sift4G	Pathogenic	0.0	D;D;D;D
Polyphen		1.0	D;D;.;D
Vest4		0.91
MutPred		0.61		.;Gain of sheet (P = 0.0344);.;.;
MVP		0.58
MPC		0.62
ClinPred		0.97	D
GERP RS		5.8
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.7
Varity_R		0.76
gMVP		0.86

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.46		Details are displayed if max score is > 0.2
DS_AG_spliceai		0.46		Position offset: 1

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

Publications

LitVar

Other links and lift over

dbSNP: rs745840866; hg19: chr4-527611;