chr4-521194-C-T

Variant names:

• chr4-521194-C-T
• rs144656165
• NM_001127178.3:c.1253C>T

Variant summary

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

The NM_001345990.2(PIGG):​c.-235C>T variant causes a 5 prime UTR premature start codon gain change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.0000291 in 1,613,908 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 (★).

• Frequency:
  • Genomes: 𝑓 0.000059 (0 hom., cov: 33)
  • Exomes 𝑓: 0.000026 (0 hom.)
• Consequence: PIGG NM_001345990.2 5_prime_UTR_premature_start_codon_gain
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 0.750

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=0.1268675).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
PIGG	NM_001127178.3	c.1253C>T	p.Thr418Met	missense_variant	Exon 7 of 13	ENST00000453061.7	NP_001120650.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
PIGG	ENST00000453061.7	c.1253C>T	p.Thr418Met	missense_variant	Exon 7 of 13	1	NM_001127178.3	ENSP00000415203.2

Frequencies

GnomAD3 genomes AF: 0.0000591 AC: 9 AN: 152156 Hom.: 0 Cov.: 33

Gnomad AFR AF: 0.000121

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.0000654

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.00

Gnomad SAS AF: 0.00

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.0000294

Gnomad OTH AF: 0.000478

GnomAD3 exomes AF: 0.0000358 AC: 9 AN: 251484 Hom.: 0 AF XY: 0.0000368 AC XY: 5 AN XY: 135914

Gnomad AFR exome AF: 0.000185

Gnomad AMR exome AF: 0.00

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.0000544

Gnomad SAS exome AF: 0.0000327

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.0000264

Gnomad OTH exome AF: 0.000163

GnomAD4 exome AF: 0.0000260 AC: 38 AN: 1461752 Hom.: 0 Cov.: 31 AF XY: 0.0000193 AC XY: 14 AN XY: 727186

Gnomad4 AFR exome AF: 0.0000299

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.0000252

Gnomad4 SAS exome AF: 0.0000696

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.0000252

Gnomad4 OTH exome AF: 0.0000331

GnomAD4 genome AF: 0.0000591 AC: 9 AN: 152156 Hom.: 0 Cov.: 33 AF XY: 0.0000942 AC XY: 7 AN XY: 74306

Gnomad4 AFR AF: 0.000121

Gnomad4 AMR AF: 0.0000654

Gnomad4 ASJ AF: 0.00

Gnomad4 EAS AF: 0.00

Gnomad4 SAS AF: 0.00

Gnomad4 FIN AF: 0.00

Gnomad4 NFE AF: 0.0000294

Gnomad4 OTH AF: 0.000478

Alfa AF: 0.000127 Hom.: 0

Bravo AF: 0.0000491

ESP6500AA AF: 0.000227 AC: 1

ESP6500EA AF: 0.00 AC: 0

ExAC AF: 0.0000412 AC: 5

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Intellectual disability, autosomal recessive 53 Uncertain:1

Sep 13, 2024

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change replaces threonine, which is neutral and polar, with methionine, which is neutral and non-polar, at codon 418 of the PIGG protein (p.Thr418Met). This variant is present in population databases (rs144656165, gnomAD 0.02%). 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: 583350). Invitae Evidence Modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) indicates that this missense variant is not expected to disrupt PIGG protein function with a negative 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	Benign	0.078
BayesDel_addAF	Benign	-0.37	T
BayesDel_noAF	Benign	-0.49
CADD	Benign	19
DANN	Uncertain	0.99
DEOGEN2	Benign	0.087	.;T;T;.;.
Eigen	Benign	-0.42
Eigen_PC	Benign	-0.60
FATHMM_MKL	Benign	0.35	N
LIST_S2	Benign	0.77	T;T;T;T;T
M_CAP	Benign	0.013	T
MetaRNN	Benign	0.13	T;T;T;T;T
MetaSVM	Benign	-0.92	T
MutationAssessor	Uncertain	2.5	M;M;.;.;.
PrimateAI	Benign	0.27	T
PROVEAN	Uncertain	-2.5	D;D;D;D;D
REVEL	Benign	0.096
Sift	Uncertain	0.023	D;D;D;D;T
Sift4G	Benign	0.16	T;T;T;T;T
Polyphen		1.0	D;D;.;D;D
Vest4		0.21
MVP		0.51
MPC		0.20
ClinPred		0.16	T
GERP RS		1.1
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.1
Varity_R		0.021
gMVP		0.29

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

Other links and lift over

dbSNP: rs144656165; hg19: chr4-514983;