chr4-499429-G-T

Position:

• chr4-499429-G-T

Variant summary

Our verdict is Uncertain significance. Variant got 1 ACMG points: 2P and 1B. PM2 BP4

The NM_001127178.3(PIGG):​c.94G>T​(p.Val32Phe) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000000687 in 1,454,866 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 12/21 in silico tools predict a benign outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★).

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 6.9e-7 (0 hom.)
• Consequence: PIGG NM_001127178.3 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 2.25

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 1 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (MetaRNN=0.39251453).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
PIGG	NM_001127178.3	c.94G>T	p.Val32Phe	missense_variant	1/13	ENST00000453061.7	NP_001120650.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
PIGG	ENST00000453061.7	c.94G>T	p.Val32Phe	missense_variant	1/13	1	NM_001127178.3	ENSP00000415203	P4

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 6.87e-7 AC: 1 AN: 1454866 Hom.: 0 Cov.: 31 AF XY: 0.00000138 AC XY: 1 AN XY: 723932

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: 9.00e-7

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 32

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Intellectual disability, autosomal recessive 53 Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Jul 26, 2022

This variant is not present in population databases (gnomAD no frequency). 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: 659844). 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: "Possibly Damaging"; Align-GVGD: "Class C0"). 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. This sequence change replaces valine, which is neutral and non-polar, with phenylalanine, which is neutral and non-polar, at codon 32 of the PIGG protein (p.Val32Phe). -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.15
BayesDel_addAF	Benign	-0.083	T
BayesDel_noAF	Benign	-0.36
CADD	Benign	23
DANN	Uncertain	0.99
DEOGEN2	Benign	0.0091	.;T;.
Eigen	Benign	0.15
Eigen_PC	Benign	0.11
FATHMM_MKL	Benign	0.19	N
LIST_S2	Uncertain	0.89	D;D;D
M_CAP	Benign	0.036	D
MetaRNN	Benign	0.39	T;T;T
MetaSVM	Benign	-1.1	T
MutationAssessor	Uncertain	2.4	M;M;M
MutationTaster	Benign	0.97	D;D;D;D;D;D;D;N
PrimateAI	Uncertain	0.66	T
PROVEAN	Benign	-1.6	N;N;N
REVEL	Benign	0.094
Sift	Uncertain	0.0050	D;D;D
Sift4G	Benign	0.72	T;T;T
Polyphen		0.97	D;P;D
Vest4		0.56
MutPred		0.35		Gain of glycosylation at S34 (P = 0.0291);Gain of glycosylation at S34 (P = 0.0291);Gain of glycosylation at S34 (P = 0.0291);
MVP		0.33
MPC		0.67
ClinPred		0.96	D
GERP RS		3.5
Varity_R		0.21
gMVP		0.65

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: rs1366589970; hg19: chr4-493218;