rs746477290

Variant names:

• chr4-516116-A-G
• rs746477290
• NM_001127178.3:c.1045A>G

Variant summary

Our verdict is Uncertain significance. The variant received 4 ACMG points: 4P and 0B. PM2 PP3_Moderate

The NM_001127178.3(PIGG):​c.1045A>G​(p.Arg349Gly) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000137 in 1,461,764 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. R349I) has been classified as Uncertain significance.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000014 (0 hom.)
• Consequence: PIGG NM_001127178.3 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 1.21
• Publications: 1 publications found

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]

PIGG Gene-Disease associations (from GenCC):

• intellectual disability, autosomal recessive 53

  Inheritance: AR Classification: DEFINITIVE, STRONG Submitted by: Ambry Genetics, Labcorp Genetics (formerly Invitae)

ACMG classification

Our verdict: Uncertain_significance. The variant received 4 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.927

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
PIGG	NM_001127178.3	c.1045A>G	p.Arg349Gly	missense_variant	Exon 6 of 13	ENST00000453061.7	NP_001120650.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
PIGG	ENST00000453061.7	c.1045A>G	p.Arg349Gly	missense_variant	Exon 6 of 13	1	NM_001127178.3	ENSP00000415203.2

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD2 exomes AF: 0.00000795 AC: 2 AN: 251494 AF XY: 0.00

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.00

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.0000544

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00000879

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000137 AC: 2 AN: 1461764 Hom.: 0 Cov.: 31 AF XY: 0.00 AC XY: 0 AN XY: 727196

African (AFR) AF: 0.00 AC: 0 AN: 33480

American (AMR) AF: 0.00 AC: 0 AN: 44724

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26136

East Asian (EAS) AF: 0.0000252 AC: 1 AN: 39700

South Asian (SAS) AF: 0.00 AC: 0 AN: 86254

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53414

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5768

European-Non Finnish (NFE) AF: 8.99e-7 AC: 1 AN: 1111894

Other (OTH) AF: 0.00 AC: 0 AN: 60394

GnomAD4 genome Cov.: 32

ExAC AF: 0.00000824 AC: 1

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Intellectual disability, autosomal recessive 53 Uncertain:1

Apr 22, 2024

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change replaces arginine, which is basic and polar, with glycine, which is neutral and non-polar, at codon 349 of the PIGG protein (p.Arg349Gly). This variant is present in population databases (rs746477290, gnomAD 0.006%). This variant has not been reported in the literature in individuals affected with PIGG-related conditions. ClinVar contains an entry for this variant (Variation ID: 476311). 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 with a positive predictive value of 80%. 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.

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.75
BayesDel_addAF	Uncertain	0.13	D
BayesDel_noAF	Uncertain	0.11
CADD	Uncertain	23
DANN	Uncertain	1.0
DEOGEN2	Benign	0.0	.;T;T;.;.;.
Eigen	Benign	0.14
Eigen_PC	Benign	0.067
FATHMM_MKL	Uncertain	0.76	D
LIST_S2	Pathogenic	0.97	D;D;D;D;D;D
M_CAP	Benign	0.013	T
MetaRNN	Pathogenic	0.93	D;D;D;D;D;D
MetaSVM	Benign	-0.73	T
MutationAssessor	Uncertain	2.7	M;M;.;.;.;.
PhyloP100		1.2
PrimateAI	Uncertain	0.58	T
PROVEAN	Uncertain	-3.8	D;D;D;D;D;D
REVEL	Uncertain	0.43
Sift	Uncertain	0.029	D;D;D;T;T;D
Sift4G	Benign	0.35	T;T;T;T;T;T
Vest4		0.91
ClinPred		0.97	D
GERP RS		3.7
Varity_R		0.44
gMVP		0.79
Mutation Taster		=44/56	disease causing

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.0		Details are displayed if max score is > 0.2

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

Other links and lift over

dbSNP: rs746477290; hg19: chr4-509905;