4-499358-T-C

Variant summary

Our verdict is Uncertain significance. Variant got 0 ACMG points: 2P and 2B. PM2 BP4_Moderate

The NM_001127178.3(PIGG):c.23T>C(p.Phe8Ser) variant causes a missense change. The variant allele was found at a frequency of 0.0000193 in 1,609,524 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign 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. F8L) has been classified as Likely benign.

• Frequency:
  • Genomes: 𝑓 0.000053 (0 hom., cov: 32)
  • Exomes 𝑓: 0.000016 (0 hom.)
• Consequence: PIGG NM_001127178.3 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:2
• Conservation: PhyloP100: 4.00

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 0 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (MetaRNN=0.24645033).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
PIGG	NM_001127178.3	c.23T>C	p.Phe8Ser	missense_variant	1/13	ENST00000453061.7

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
PIGG	ENST00000453061.7	c.23T>C	p.Phe8Ser	missense_variant	1/13	1	NM_001127178.3	P4

Frequencies

GnomAD3 genomes AF: 0.0000526 AC: 8 AN: 152234 Hom.: 0 Cov.: 32

Gnomad AFR AF: 0.0000723

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.00

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.000965

Gnomad SAS AF: 0.00

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.00

Gnomad OTH AF: 0.00

GnomAD3 exomes AF: 0.0000738 AC: 18 AN: 243910 Hom.: 0 AF XY: 0.0000905 AC XY: 12 AN XY: 132638

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.00

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.000930

Gnomad SAS exome AF: 0.0000328

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.0000158 AC: 23 AN: 1457172 Hom.: 0 Cov.: 31 AF XY: 0.0000179 AC XY: 13 AN XY: 725106

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.0000224

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.000504

Gnomad4 SAS exome AF: 0.0000116

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00

Gnomad4 OTH exome AF: 0.0000166

GnomAD4 genome AF: 0.0000525 AC: 8 AN: 152352 Hom.: 0 Cov.: 32 AF XY: 0.0000537 AC XY: 4 AN XY: 74508

Gnomad4 AFR AF: 0.0000721

Gnomad4 AMR AF: 0.00

Gnomad4 ASJ AF: 0.00

Gnomad4 EAS AF: 0.000967

Gnomad4 SAS AF: 0.00

Gnomad4 FIN AF: 0.00

Gnomad4 NFE AF: 0.00

Gnomad4 OTH AF: 0.00

Alfa AF: 0.0000566 Hom.: 0

Bravo AF: 0.0000264

ExAC AF: 0.0000824 AC: 10

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	Invitae	Sep 30, 2021	This sequence change replaces phenylalanine with serine at codon 8 of the PIGG protein (p.Phe8Ser). The phenylalanine residue is moderately conserved and there is a large physicochemical difference between phenylalanine and serine. This variant is present in population databases (rs182168436, ExAC 0.1%). 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: 1033298). Algorithms developed to predict the effect of missense changes on protein structure and function (SIFT, PolyPhen-2, Align-GVGD) all suggest that this variant is likely to be disruptive. 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. -
Uncertain significance, criteria provided, single submitter	clinical testing	Baylor Genetics	Jan 11, 2018	This variant was determined to be of uncertain significance according to ACMG Guidelines, 2015 [PMID:25741868]. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.79
BayesDel_addAF	Benign	-0.22	T
BayesDel_noAF	Benign	-0.16
Cadd	Uncertain	25
Dann	Uncertain	1.0
Eigen	Uncertain	0.31
Eigen_PC	Uncertain	0.24
FATHMM_MKL	Benign	0.52	D
LIST_S2	Benign	0.79	T;T;T
M_CAP	Benign	0.044	D
MetaRNN	Benign	0.25	T;T;T
MetaSVM	Benign	-1.2	T
MutationAssessor	Uncertain	2.5	M;M;M
MutationTaster	Benign	1.0	D;D;D;D;D;D;D;N
PrimateAI	Pathogenic	0.80	T
PROVEAN	Uncertain	-3.8	D;D;D
REVEL	Benign	0.23
Sift	Uncertain	0.0020	D;D;D
Sift4G	Uncertain	0.0050	D;D;D
Polyphen		0.97	D;D;D
Vest4		0.79
MVP		0.40
MPC		0.87
ClinPred		0.77	D
GERP RS		3.2
Varity_R		0.43
gMVP		0.70

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.010		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: rs182168436; hg19: chr4-493147;