4-523849-C-T

Variant summary

Our verdict is Uncertain significance. Variant got 5 ACMG points: 5P and 0B. PM2PP3_ModeratePP5

The NM_001127178.3(PIGG):c.2005C>T(p.Arg669Cys) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000094 in 1,595,968 control chromosomes in the GnomAD database, including 1 homozygotes. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. R669H) has been classified as Uncertain significance.

Frequency

Genomes: 𝑓 0.000098 ( 0 hom., cov: 33)

Exomes 𝑓: 0.000094 ( 1 hom. )

Consequence

PIGG
NM_001127178.3 missense

Scores

Clinical Significance

Conflicting classifications of pathogenicity criteria provided, conflicting classifications P:2U:2

Conservation

PhyloP100: 2.03

Variant links:

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 links:

Genome browser will be placed here

ACMG classification

Classification made for transcript

Verdict is Uncertain_significance. Variant got 5 ACMG points.

PM2

Very rare variant in population databases, with high coverage;

PP3

MetaRNN computational evidence supports a deleterious effect, 0.902

PP5

Variant 4-523849-C-T is Pathogenic according to our data. Variant chr4-523849-C-T is described in ClinVar as [Conflicting_classifications_of_pathogenicity]. Clinvar id is 225638.We mark this variant Likely_pathogenic, oryginal submissions are: {Uncertain_significance=2, Pathogenic=1}. Variant chr4-523849-C-T is described in Lovd as [Likely_pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
PIGG	NM_001127178.3 linkuse as main transcript	c.2005C>T	p.Arg669Cys	missense_variant	9/13	ENST00000453061.7

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
PIGG	ENST00000453061.7 linkuse as main transcript	c.2005C>T	p.Arg669Cys	missense_variant	9/13	1	NM_001127178.3	P4	Q5H8A4-1

Frequencies

GnomAD3 genomes

AF:

0.0000985

AC:

AN:

152224

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.0000724

Gnomad AMI

AF:

0.00

Gnomad AMR

AF:

0.000131

Gnomad ASJ

AF:

0.00

Gnomad EAS

AF:

0.000770

Gnomad SAS

AF:

0.00

Gnomad FIN

AF:

0.00

Gnomad MID

AF:

0.00

Gnomad NFE

AF:

0.0000882

Gnomad OTH

AF:

0.00

GnomAD3 exomes

AF:

0.0000667

AC:

AN:

209920

Hom.:

AF XY:

0.0000525

AC XY:

AN XY:

114352

show subpopulations

Gnomad AFR exome

AF:

0.00

Gnomad AMR exome

AF:

0.000198

Gnomad ASJ exome

AF:

0.00

Gnomad EAS exome

AF:

0.000130

Gnomad SAS exome

AF:

0.00

Gnomad FIN exome

AF:

0.00

Gnomad NFE exome

AF:

0.0000660

Gnomad OTH exome

AF:

0.00

GnomAD4 exome

AF:

0.0000935

AC:

135

AN:

1443628

Hom.:

Cov.:

AF XY:

0.0000990

AC XY:

AN XY:

716814

show subpopulations

Gnomad4 AFR exome

AF:

0.00

Gnomad4 AMR exome

AF:

0.000168

Gnomad4 ASJ exome

AF:

0.00

Gnomad4 EAS exome

AF:

0.00258

Gnomad4 SAS exome

AF:

0.0000356

Gnomad4 FIN exome

AF:

0.00

Gnomad4 NFE exome

AF:

0.0000208

Gnomad4 OTH exome

AF:

0.0000168

GnomAD4 genome

AF:

0.0000985

AC:

AN:

152340

Hom.:

Cov.:

AF XY:

0.0000671

AC XY:

AN XY:

74478

show subpopulations

Gnomad4 AFR

AF:

0.0000722

Gnomad4 AMR

AF:

0.000131

Gnomad4 ASJ

AF:

0.00

Gnomad4 EAS

AF:

0.000772

Gnomad4 SAS

AF:

0.00

Gnomad4 FIN

AF:

0.00

Gnomad4 NFE

AF:

0.0000882

Gnomad4 OTH

AF:

0.00

Alfa

AF:

0.0000364

Hom.:

Bravo

AF:

0.0000756

ESP6500AA

AF:

0.00

AC:

ESP6500EA

AF:

0.000117

AC:

ExAC

AF:

0.0000913

AC:

Asia WGS

AF:

0.000289

AC:

AN:

3478

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Pathogenic:2Uncertain:2

Revision: criteria provided, conflicting classifications

LINK: link

Submissions by phenotype

Intellectual disability, autosomal recessive 53

Pathogenic:1Uncertain:1

Pathogenic, no assertion criteria provided	literature only	OMIM	Jan 20, 2023	- -
Uncertain significance, criteria provided, single submitter	clinical testing	Invitae	Jan 17, 2024	This sequence change replaces arginine, which is basic and polar, with cysteine, which is neutral and slightly polar, at codon 669 of the PIGG protein (p.Arg669Cys). This variant is present in population databases (rs372392424, gnomAD 0.02%). This missense change has been observed in individual(s) with intellectual disability, seizures, and hypotonia (PMID: 26996948). ClinVar contains an entry for this variant (Variation ID: 225638). 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. -

Hyperphosphatasia with intellectual disability syndrome 1

Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Institute for Genomic Statistics and Bioinformatics, University Hospital Bonn

- -

not provided

Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

GeneDx

Jun 29, 2023

Published functional studies demonstrate a damaging effect: impairs the conversion of GPI precursor H7 to H8 (Makrythanasis et al., 2016); In silico analysis supports that this missense variant has a deleterious effect on protein structure/function; This variant is associated with the following publications: (PMID: Ishida2020[Functional Study], 27870114, 26996948) -

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Pathogenic

0.57

BayesDel_addAF

Uncertain

0.13

BayesDel_noAF

Pathogenic

0.23

Cadd

Uncertain

Dann

Pathogenic

1.0

Eigen

Uncertain

0.66

Eigen_PC

Uncertain

0.58

FATHMM_MKL

Uncertain

0.85

LIST_S2

Pathogenic

0.98

D;D;D;D

M_CAP

Benign

0.040

MetaRNN

Pathogenic

0.90

D;D;D;D

MetaSVM

Uncertain

0.10

MutationTaster

Benign

1.0

D;D;D;D;D

PrimateAI

Uncertain

0.72

PROVEAN

Pathogenic

-7.0

D;D;D;D

REVEL

Pathogenic

0.70

Sift

Uncertain

0.0010

D;D;D;D

Sift4G

Pathogenic

0.0

D;D;D;D

Polyphen

1.0

D;D;.;D

Vest4

0.97

MVP

0.80

MPC

0.81

ClinPred

0.80

GERP RS

4.7

RBP_binding_hub_radar

0.0

RBP_regulation_power_radar

1.7

Varity_R

0.73

gMVP

0.85

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

Publications

LitVar

Below is the list of publications found by LitVar. It may be empty.

Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

ACMG classification

Transcripts

RefSeq

Ensembl

Frequencies

ClinVar

Submissions by phenotype

Computational scores

Splicing

Publications

LitVar

Other links and lift over