rs1555694236

Positions:

• chr18-62146025-C-A

Variant summary

Our verdict is Likely pathogenic. Variant got 8 ACMG points: 8P and 0B. PM1 PM2 PP3_Strong

The NM_176787.5(PIGN):​c.806G>T​(p.Gly269Val) variant causes a missense, splice region change. The variant allele was found at a frequency of 0.000000793 in 1,261,642 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. 1/1 splice prediction tools predict no significant impact on normal splicing. Variant has been reported in ClinVar as Uncertain significance (★).

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 7.9e-7 (0 hom.)
• Consequence: PIGN NM_176787.5 missense, splice_region
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 6.96

Genes affected

PIGN (HGNC:8967): (phosphatidylinositol glycan anchor biosynthesis class N) This gene encodes a protein that is involved in glycosylphosphatidylinositol (GPI)-anchor biosynthesis. The GPI-anchor is a glycolipid found on many blood cells and serves to anchor proteins to the cell surface. This protein is expressed in the endoplasmic reticulum and transfers phosphoethanolamine (EtNP) to the first mannose of the GPI anchor. Two alternatively spliced variants, which encode an identical isoform, have been reported. [provided by RefSeq, Jul 2008]

ACMG classification

Verdict is Likely_pathogenic. Variant got 8 ACMG points.

• PM1: In a hotspot region, there are 3 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 0 benign, 4 uncertain in NM_176787.5
• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.96

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
PIGN	NM_176787.5	c.806G>T	p.Gly269Val	missense_variant, splice_region_variant	10/31	ENST00000640252.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
PIGN	ENST00000640252.2	c.806G>T	p.Gly269Val	missense_variant, splice_region_variant	10/31	1	NM_176787.5	P1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 7.93e-7 AC: 1 AN: 1261642 Hom.: 0 Cov.: 18 AF XY: 0.00000158 AC XY: 1 AN XY: 634104

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: 0.0000136

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00

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

Multiple congenital anomalies-hypotonia-seizures syndrome 1 Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Invitae

Aug 31, 2021

This sequence change replaces glycine with valine at codon 269 of the PIGN protein (p.Gly269Val). The glycine residue is highly conserved and there is a moderate physicochemical difference between glycine and valine. This variant is not present in population databases (ExAC no frequency). This variant has not been reported in the literature in individuals affected with PIGN-related conditions. 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. Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant may disrupt the consensus splice site. 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	0.98
BayesDel_addAF	Pathogenic	0.31	D
BayesDel_noAF	Pathogenic	0.21
CADD	Pathogenic	31
DANN	Uncertain	1.0
DEOGEN2	Uncertain	0.53	D;.;D;D;D;.;.;.;.;.;D;.;.;D;.;D;.;.;.;.;.;.;.;.;.
Eigen	Pathogenic	0.97
Eigen_PC	Pathogenic	0.92
FATHMM_MKL	Pathogenic	0.99	D
M_CAP	Uncertain	0.15	D
MetaRNN	Pathogenic	0.96	D;D;D;D;D;D;D;D;D;D;D;D;D;D;D;D;D;D;D;D;D;D;D;D;D
MetaSVM	Uncertain	-0.24	T
MutationAssessor	Pathogenic	3.6	H;.;H;H;H;.;.;.;.;.;H;.;.;H;.;H;.;.;.;.;.;.;.;.;.
MutationTaster	Benign	1.0	D;D
PrimateAI	Uncertain	0.52	T
Polyphen		1.0	D;.;D;D;D;.;.;.;.;.;D;.;.;D;.;D;.;.;.;.;.;.;.;.;.
Vest4		0.97, 0.97
MutPred		0.83		Loss of disorder (P = 0.0318);Loss of disorder (P = 0.0318);Loss of disorder (P = 0.0318);Loss of disorder (P = 0.0318);Loss of disorder (P = 0.0318);Loss of disorder (P = 0.0318);Loss of disorder (P = 0.0318);Loss of disorder (P = 0.0318);.;.;Loss of disorder (P = 0.0318);Loss of disorder (P = 0.0318);Loss of disorder (P = 0.0318);Loss of disorder (P = 0.0318);Loss of disorder (P = 0.0318);Loss of disorder (P = 0.0318);Loss of disorder (P = 0.0318);Loss of disorder (P = 0.0318);Loss of disorder (P = 0.0318);Loss of disorder (P = 0.0318);Loss of disorder (P = 0.0318);Loss of disorder (P = 0.0318);Loss of disorder (P = 0.0318);Loss of disorder (P = 0.0318);Loss of disorder (P = 0.0318);
MVP		0.85
MPC		0.21
ClinPred		1.0	D
GERP RS		5.8
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.7
Varity_R		0.99
gMVP		0.94

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.030		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: rs1555694236; hg19: chr18-59813258;