chr18-62082682-G-A

Variant names:

Variant summary

Our verdict is Uncertain significance. The variant received 2 ACMG points: 2P and 0B. PM2

The NM_176787.5(PIGN):c.2567C>T(p.Ser856Leu) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.000019 in 1,528,862 control chromosomes in the GnomAD database, with no homozygous occurrence. Variant has been reported in ClinVar as Uncertain significance (★★). Synonymous variant affecting the same amino acid position (i.e. S856S) has been classified as Likely benign.

Frequency

Genomes: 𝑓 0.000013 ( 0 hom., cov: 32)

Exomes 𝑓: 0.000020 ( 0 hom. )

Consequence

PIGN
NM_176787.5 missense

Scores

Clinical Significance

Uncertain significance criteria provided, multiple submitters, no conflicts U:3

Conservation

PhyloP100: 8.40

Publications

5 publications found

Variant links:

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]

PIGN Gene-Disease associations (from GenCC):

multiple congenital anomalies-hypotonia-seizures syndrome 1
Inheritance: AR Classification: DEFINITIVE, STRONG, MODERATE, SUPPORTIVE Submitted by: Labcorp Genetics (formerly Invitae), Ambry Genetics, G2P, Orphanet, ClinGen, PanelApp Australia
Fryns syndrome
Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet

PIGN links:

Genome browser will be placed here

ACMG classification

Classification was made for transcript

Our verdict: Uncertain_significance. The variant received 2 ACMG points.

PM2

Very rare variant in population databases, with high coverage;

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
PIGN	NM_176787.5 link	c.2567C>T	p.Ser856Leu	missense_variant	Exon 28 of 31	ENST00000640252.2	NP_789744.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein
PIGN	ENST00000640252.2 link	c.2567C>T	p.Ser856Leu	missense_variant	Exon 28 of 31	1	NM_176787.5	ENSP00000492233.1
PIGN	ENST00000400334.7 link	c.2567C>T	p.Ser856Leu	missense_variant	Exon 27 of 30	1		ENSP00000383188.2
PIGN	ENST00000638424.1 link	n.*535C>T		non_coding_transcript_exon_variant	Exon 26 of 29	5		ENSP00000491963.1
PIGN	ENST00000638424.1 link	n.*535C>T		3_prime_UTR_variant	Exon 26 of 29	5		ENSP00000491963.1

Frequencies

GnomAD3 genomes

AF:

0.0000132

AC:

AN:

151956

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.0000242

Gnomad AMI

AF:

0.00

Gnomad AMR

AF:

0.00

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:

0.0000147

Gnomad OTH

AF:

0.00

GnomAD2 exomes

AF:

0.0000118

AC:

AN:

169118

AF XY:

0.0000112

show subpopulations

Gnomad AFR exome

AF:

0.000104

Gnomad AMR exome

AF:

0.00

Gnomad ASJ exome

AF:

0.00

Gnomad EAS exome

AF:

0.0000807

Gnomad FIN exome

AF:

0.00

Gnomad NFE exome

AF:

0.00

Gnomad OTH exome

AF:

0.00

GnomAD4 exome

AF:

0.0000196

AC:

AN:

1376906

Hom.:

Cov.:

AF XY:

0.0000264

AC XY:

AN XY:

681310

show subpopulations

African (AFR)

AF:

0.0000637

AC:

AN:

31390

American (AMR)

AF:

0.00

AC:

AN:

36168

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

24988

East Asian (EAS)

AF:

0.0000273

AC:

AN:

36644

South Asian (SAS)

AF:

0.0000513

AC:

AN:

78010

European-Finnish (FIN)

AF:

0.00

AC:

AN:

49770

Middle Eastern (MID)

AF:

0.000178

AC:

AN:

5604

European-Non Finnish (NFE)

AF:

0.0000151

AC:

AN:

1056992

Other (OTH)

AF:

0.0000523

AC:

AN:

57340

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.469

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Age Distribution

Exome Het

Variant carriers

<30

30-35

35-40

40-45

45-50

50-55

55-60

60-65

65-70

70-75

75-80

>80

Age

GnomAD4 genome

AF:

0.0000132

AC:

AN:

151956

Hom.:

Cov.:

AF XY:

0.00

AC XY:

AN XY:

74218

show subpopulations

⚠️ The allele balance in gnomAD version 4 Genomes is significantly skewed from the expected value of 0.5.

African (AFR)

AF:

0.0000242

AC:

AN:

41398

American (AMR)

AF:

0.00

AC:

AN:

15270

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

3470

East Asian (EAS)

AF:

0.00

AC:

AN:

5192

South Asian (SAS)

AF:

0.00

AC:

AN:

4828

European-Finnish (FIN)

AF:

0.00

AC:

AN:

10568

Middle Eastern (MID)

AF:

0.00

AC:

AN:

316

European-Non Finnish (NFE)

AF:

0.0000147

AC:

AN:

67914

Other (OTH)

AF:

0.00

AC:

AN:

2088

⚠️ The allele balance in gnomAD version 4 Genomes is significantly skewed from the expected value of 0.5. (p-value = 0.00000000770867), which strongly suggests a high chance of mosaicism in these individuals.

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.400

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Alfa

AF:

0.00

Hom.:

Bravo

AF:

0.0000264

ExAC

AF:

0.00000862

AC:

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:3

Revision: criteria provided, multiple submitters, no conflicts

LINK: link

Submissions by phenotype

Inborn genetic diseases

Uncertain:1

Nov 06, 2023

Ambry Genetics

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

The c.2567C>T (p.S856L) alteration is located in exon 28 (coding exon 25) of the PIGN gene. This alteration results from a C to T substitution at nucleotide position 2567, causing the serine (S) at amino acid position 856 to be replaced by a leucine (L). Based on insufficient or conflicting evidence, the clinical significance of this alteration remains unclear.

Multiple congenital anomalies-hypotonia-seizures syndrome 1

Uncertain:1

Jul 29, 2024

Labcorp Genetics (formerly Invitae), Labcorp

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

This sequence change replaces serine, which is neutral and polar, with leucine, which is neutral and non-polar, at codon 856 of the PIGN protein (p.Ser856Leu). The frequency data for this variant in the population databases is considered unreliable, as metrics indicate poor data quality at this position in the gnomAD database. This variant has not been reported in the literature in individuals affected with PIGN-related conditions. ClinVar contains an entry for this variant (Variation ID: 451887). 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 PIGN 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.

not provided

Uncertain:1

Jun 10, 2025

GeneDx

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

Not observed at significant frequency in large population cohorts (gnomAD); In silico analysis supports that this missense variant has a deleterious effect on protein structure/function; Has not been previously published as pathogenic or benign to our knowledge

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Benign

0.22

BayesDel_addAF

Uncertain

0.13

BayesDel_noAF

Uncertain

-0.050

CADD

Pathogenic

(source)

DANN

Pathogenic

1.0

DEOGEN2

Benign

0.19

T;.;T;T;T;.;.;.;.;.;T;.;.;T;.;T;.;.

Eigen

Pathogenic

0.82

Eigen_PC

Pathogenic

0.81

FATHMM_MKL

Pathogenic

0.98

LIST_S2

Benign

0.0

.;.;.;.;.;.;D;.;D;D;.;D;D;.;D;D;D;D

M_CAP

Benign

0.074

MetaRNN

Uncertain

0.62

D;D;D;D;D;D;D;D;D;D;D;D;D;D;D;D;D;D

MetaSVM

Benign

-0.50

MutationAssessor

Uncertain

2.9

M;.;M;M;M;.;.;.;.;.;M;.;.;M;.;M;.;.

PhyloP100

8.4

PrimateAI

Uncertain

0.58

PROVEAN

Benign

0.0

.;.;.;D;.;.;.;.;.;.;D;.;.;.;.;.;.;.

REVEL

Benign

0.0

Sift

Pathogenic

0.0

.;.;.;D;.;.;.;.;.;.;D;.;.;.;.;.;.;.

Sift4G

Pathogenic

0.0

.;.;.;D;.;.;.;.;.;.;D;.;.;.;.;.;.;.

Vest4

0.0

ClinPred

0.94

GERP RS

5.7

Varity_R

0.25

gMVP

0.31

Mutation Taster

=32/68

disease causing

(source)

Splicing

Name

Calibrated prediction

Score

Prediction

SpliceAI score (max)

0.040

Details are displayed if max score is > 0.2

Find out detailed SpliceAI scores and Pangolin per-transcript scores at spliceailookup.broadinstitute.org

Publications

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Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

Publications

ACMG classification

Transcripts

RefSeq

Ensembl

Frequencies

Age Distribution

ClinVar

Submissions by phenotype

Computational scores

Splicing

Publications

Other links and lift over