15-55340721-T-C

Variant summary

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

The NM_004855.5(PIGB):c.956T>C(p.Ile319Thr) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.0000484 in 1,611,100 control chromosomes in the GnomAD database, with no homozygous occurrence. Variant has been reported in ClinVar as Uncertain significance (★★).

• Frequency:
  • Genomes: 𝑓 0.000020 (0 hom., cov: 32)
  • Exomes 𝑓: 0.000051 (0 hom.)
• Consequence: PIGB NM_004855.5 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:2
• Conservation: PhyloP100: 7.38

Genes affected

PIGB (HGNC:8959): (phosphatidylinositol glycan anchor biosynthesis class B) This gene encodes a transmembrane protein that is located in the endoplasmic reticulum and is involved in GPI-anchor biosynthesis. The glycosylphosphatidylinositol (GPI) anchor is a glycolipid found on many blood cells and serves to anchor proteins to the cell surface. This gene is thought to encode a member of a family of dolichol-phosphate-mannose (Dol-P-Man) dependent mannosyltransferases. [provided by RefSeq, Jul 2008]

CCPG1 (HGNC:24227): (cell cycle progression 1) Involved in positive regulation of cell cycle and positive regulation of cell population proliferation. Predicted to be integral component of membrane. Predicted to be active in membrane. [provided by Alliance of Genome Resources, Apr 2022]

ACMG classification

Verdict is Uncertain_significance. Variant got 2 ACMG points.

• PM2: Very rare variant in population databases, with high coverage

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
PIGB	NM_004855.5	c.956T>C	p.Ile319Thr	missense_variant	8/12	ENST00000164305.10

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
PIGB	ENST00000164305.10	c.956T>C	p.Ile319Thr	missense_variant	8/12	1	NM_004855.5	P2

Frequencies

GnomAD3 genomes AF: 0.0000197 AC: 3 AN: 152132 Hom.: 0 Cov.: 32

Gnomad AFR AF: 0.0000241

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: 0.0000294

Gnomad OTH AF: 0.00

GnomAD3 exomes AF: 0.0000408 AC: 10 AN: 244934 Hom.: 0 AF XY: 0.0000527 AC XY: 7 AN XY: 132754

Gnomad AFR exome AF: 0.0000664

Gnomad AMR exome AF: 0.0000588

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad SAS exome AF: 0.000202

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00000900

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.0000514 AC: 75 AN: 1458850 Hom.: 0 Cov.: 31 AF XY: 0.0000538 AC XY: 39 AN XY: 725514

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.0000450

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.000233

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.0000468

Gnomad4 OTH exome AF: 0.0000166

GnomAD4 genome AF: 0.0000197 AC: 3 AN: 152250 Hom.: 0 Cov.: 32 AF XY: 0.0000134 AC XY: 1 AN XY: 74432

Gnomad4 AFR AF: 0.0000241

Gnomad4 AMR AF: 0.00

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: 0.00

Alfa AF: 0.0000282 Hom.: 0

Bravo AF: 0.0000189

ExAC AF: 0.0000331 AC: 4

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:2

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Inborn genetic diseases Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Ambry Genetics

Sep 29, 2022

The c.956T>C (p.I319T) alteration is located in exon 8 (coding exon 8) of the PIGB gene. This alteration results from a T to C substitution at nucleotide position 956, causing the isoleucine (I) at amino acid position 319 to be replaced by a threonine (T). Based on insufficient or conflicting evidence, the clinical significance of this alteration remains unclear. -

not provided Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Invitae

Oct 13, 2022

This sequence change replaces isoleucine, which is neutral and non-polar, with threonine, which is neutral and polar, at codon 319 of the PIGB protein (p.Ile319Thr). This variant is present in population databases (rs573654812, gnomAD 0.02%). This variant has not been reported in the literature in individuals affected with PIGB-related conditions. 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 not expected to disrupt PIGB protein function. 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	Uncertain	0.42
BayesDel_addAF	Benign	-0.14	T
BayesDel_noAF	Benign	-0.17
Cadd	Uncertain	24
Dann	Uncertain	1.0
DEOGEN2	Benign	0.081	T;T
Eigen	Uncertain	0.31
Eigen_PC	Uncertain	0.38
FATHMM_MKL	Pathogenic	0.98	D
LIST_S2	Uncertain	0.91	D;D
M_CAP	Benign	0.023	T
MetaRNN	Uncertain	0.48	T;T
MetaSVM	Benign	-0.46	T
MutationAssessor	Benign	2.0	M;.
MutationTaster	Benign	1.0	D;D
PrimateAI	Benign	0.35	T
PROVEAN	Uncertain	-3.1	D;.
REVEL	Uncertain	0.33
Sift	Uncertain	0.0070	D;.
Sift4G	Uncertain	0.0060	D;D
Polyphen		0.32	B;.
Vest4		0.59
MVP		0.83
MPC		0.15
ClinPred		0.21	T
GERP RS		5.9
Varity_R		0.22
gMVP		0.54

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: rs573654812; hg19: chr15-55632919;