NM_002641.4:c.1183G>A

Variant names:

• chrX-15324670-C-T
• rs1060499666
• NM_002641.4:c.1183G>A

Variant summary

Our verdict is Uncertain significance. The variant received 5 ACMG points: 5P and 0B. PM2 PP3_Moderate PP5

The NM_002641.4(PIGA):​c.1183G>A​(p.Glu395Lys) variant causes a missense change involving the alteration of a conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. E395G) has been classified as Uncertain significance.

• Frequency: Genomes: not found (cov: 23)
• Consequence: PIGA NM_002641.4 missense
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications P:1 U:1
• Conservation: PhyloP100: 7.30
• Publications: 2 publications found

Genes affected

PIGA (HGNC:8957): (phosphatidylinositol glycan anchor biosynthesis class A) This gene encodes a protein required for synthesis of N-acetylglucosaminyl phosphatidylinositol (GlcNAc-PI), the first intermediate in the biosynthetic pathway of GPI anchor. The GPI anchor is a glycolipid found on many blood cells and which serves to anchor proteins to the cell surface. Paroxysmal nocturnal hemoglobinuria, an acquired hematologic disorder, has been shown to result from mutations in this gene. Alternate splice variants have been characterized. A related pseudogene is located on chromosome 12. [provided by RefSeq, Jun 2010]

PIGA Gene-Disease associations (from GenCC):

• multiple congenital anomalies-hypotonia-seizures syndrome 2

  Inheritance: XL Classification: DEFINITIVE, STRONG, MODERATE, SUPPORTIVE Submitted by: G2P, Illumina, Labcorp Genetics (formerly Invitae), Orphanet
• infantile spasms

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
• malignant migrating partial seizures of infancy

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
• ferro-cerebro-cutaneous syndrome

  Inheritance: XL Classification: SUPPORTIVE Submitted by: Orphanet
• paroxysmal nocturnal hemoglobinuria

  Inheritance: Unknown Classification: SUPPORTIVE Submitted by: Orphanet

ACMG classification

Our verdict: Uncertain_significance. The variant received 5 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.848
• PP5: Variant X-15324670-C-T is Pathogenic according to our data. Variant chrX-15324670-C-T is described in ClinVar as Conflicting_classifications_of_pathogenicity. ClinVar VariationId is 397534.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
PIGA	NM_002641.4	c.1183G>A	p.Glu395Lys	missense_variant	Exon 5 of 6	ENST00000333590.6	NP_002632.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
PIGA	ENST00000333590.6	c.1183G>A	p.Glu395Lys	missense_variant	Exon 5 of 6	1	NM_002641.4	ENSP00000369820.3

Frequencies

GnomAD3 genomes Cov.: 23

GnomAD4 exome Cov.: 27

GnomAD4 genome Cov.: 23

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Pathogenic:1 Uncertain:1

Revision: criteria provided, conflicting classifications

Submissions by phenotype

Multiple congenital anomalies-hypotonia-seizures syndrome 2 Pathogenic:1 Uncertain:1

Aug 12, 2014

Center of Genomic medicine, Geneva, University Hospital of Geneva

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Nov 06, 2020

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change replaces glutamic acid with lysine at codon 395 of the PIGA protein (p.Glu395Lys). The glutamic acid residue is moderately conserved and there is a small physicochemical difference between glutamic acid and lysine. 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. Algorithms developed to predict the effect of missense changes on protein structure and function are either unavailable or do not agree on the potential impact of this missense change (SIFT: "Tolerated"; PolyPhen-2: "Possibly Damaging"; Align-GVGD: "Class C0"). This variant has been observed in individual(s) with clinical features of PIGA-congenital disorder of glycosylation (PMID: 27353043). This variant is also known as c.481G>A (p.Glu161Lys). ClinVar contains an entry for this variant (Variation ID: 397534). This variant is not present in population databases (ExAC no frequency). -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Uncertain	0.54
BayesDel_addAF	Pathogenic	0.29	D
BayesDel_noAF	Pathogenic	0.18
CADD	Pathogenic	26
DANN	Pathogenic	1.0
DEOGEN2	Uncertain	0.64	D;D;T;.;.;.
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Pathogenic	0.99	.;D;D;D;D;D
M_CAP	Pathogenic	0.72	D
MetaRNN	Pathogenic	0.85	D;D;D;D;D;D
MetaSVM	Uncertain	0.25	D
MutationAssessor	Pathogenic	3.4	M;M;.;.;.;.
PhyloP100		7.3
PrimateAI	Uncertain	0.57	T
PROVEAN	Uncertain	-3.3	D;.;.;.;.;.
REVEL	Pathogenic	0.68
Sift	Uncertain	0.0090	D;.;.;.;.;.
Sift4G	Uncertain	0.0090	D;D;.;D;D;.
Polyphen		1.0	D;D;.;.;D;.
Vest4		0.54
MutPred		0.60		Gain of MoRF binding (P = 0.0053);Gain of MoRF binding (P = 0.0053);.;.;.;.;
MVP		0.86
MPC		1.2
ClinPred		0.99	D
GERP RS		5.9
PromoterAI		-0.0088	Neutral
Varity_R		0.66
gMVP		0.97
Mutation Taster		=22/78	disease causing (ClinVar)

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

Other links and lift over

dbSNP: rs1060499666; hg19: chrX-15342792;