16-8811080-G-T

Variant names:

• chr16-8811080-G-T
• rs104894530
• NM_000303.3:c.349G>T

Variant summary

Our verdict is Likely pathogenic. Variant got 6 ACMG points: 6P and 0B. PM1 PM2 PP3 PP5

The NM_000303.3(PMM2):​c.349G>T​(p.Gly117Cys) variant causes a missense, splice region 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. 14/23 in silico tools predict a damaging outcome for this variant. 2/3 splice prediction tools predicting alterations to normal splicing. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars).

• Frequency:
  • Genomes: not found (cov: 34)
  • Exomes 𝑓: 0.0 (0 hom.)
  • Failed GnomAD Quality Control
• Consequence: PMM2 NM_000303.3 missense, splice_region
• Scores: Splicing: ADA: 0.9728
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications P:2 U:1
• Conservation: PhyloP100: 9.79

Genes affected

PMM2 (HGNC:9115): (phosphomannomutase 2) The protein encoded by this gene catalyzes the isomerization of mannose 6-phosphate to mannose 1-phosphate, which is a precursor to GDP-mannose necessary for the synthesis of dolichol-P-oligosaccharides. Mutations in this gene have been shown to cause defects in glycoprotein biosynthesis, which manifests as carbohydrate-deficient glycoprotein syndrome type I. [provided by RefSeq, Jul 2008]

ACMG classification

Verdict is Likely_pathogenic. Variant got 6 ACMG points.

• PM1: In a chain Phosphomannomutase 2 (size 244) in uniprot entity PMM2_HUMAN there are 79 pathogenic changes around while only 2 benign (98%) in NM_000303.3
• PM2: Very rare variant in population databases, with high coverage
• PP3: Splicing scoreres supports a deletorius effect: Scorers claiming Pathogenic: dbscSNV1_ADA, dbscSNV1_RF. No scorers claiming Uncertain. Scorers claiming Benign: max_spliceai.
• PP5: Variant 16-8811080-G-T is Pathogenic according to our data. Variant chr16-8811080-G-T is described in ClinVar as [Conflicting_classifications_of_pathogenicity]. Clinvar id is 694260.We mark this variant Likely_pathogenic, oryginal submissions are: {Likely_pathogenic=1, Uncertain_significance=1, Pathogenic=1}.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
PMM2	NM_000303.3	c.349G>T	p.Gly117Cys	missense_variant, splice_region_variant	Exon 5 of 8	ENST00000268261.9	NP_000294.1
PMM2	XM_047434215.1	c.100G>T	p.Gly34Cys	missense_variant, splice_region_variant	Exon 3 of 6		XP_047290171.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
PMM2	ENST00000268261.9	c.349G>T	p.Gly117Cys	missense_variant, splice_region_variant	Exon 5 of 8	1	NM_000303.3	ENSP00000268261.4

Frequencies

GnomAD3 genomes Cov.: 34

GnomAD4 exome Data not reliable, filtered out with message: AC0 AF: 0.00 AC: 0 AN: 1395586 Hom.: 0 Cov.: 30 AF XY: 0.00 AC XY: 0 AN XY: 690788

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: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 34

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Pathogenic:2 Uncertain:1

Revision: criteria provided, conflicting classifications

Submissions by phenotype

PMM2-congenital disorder of glycosylation Pathogenic:2 Uncertain:1

Aug 20, 2021

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change replaces glycine with cysteine at codon 117 of the PMM2 protein (p.Gly117Cys). The glycine residue is highly conserved and there is a large physicochemical difference between glycine and cysteine. This variant is not present in population databases (ExAC no frequency). This variant has not been reported in the literature in individuals affected with PMM2-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 create or strengthen a 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. -

-

Pediatric Metabolic Diseases, Hacettepe University

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Nov 01, 2020

Pediatrics, MediClubGeorgia

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The PMM2 variant c.349G>T p.(Gly117Cys) causes an amino acid change from Gly to Cys at position 117. The substitution is in close proximity to the highly conserved acceptor splice site. This variant is absent in population databases and in clinvar is submitted as a likely pathogenic. Algorithms developed to predict the effect of missense variants showed:PolyPhen: Probablydamaging; Align-GVGD: C0; SIFT: Deleterious; MutationTaster: Disease-causing; Conservation_nt: high; Conservation_aa: high 2/2 likely splice effect; -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.97
BayesDel_addAF	Pathogenic	0.58	D
BayesDel_noAF	Pathogenic	0.60
CADD	Pathogenic	34
DANN	Uncertain	1.0
DEOGEN2	Pathogenic	0.94	D;D
Eigen	Pathogenic	1.0
Eigen_PC	Pathogenic	0.95
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Pathogenic	0.99	D;D
M_CAP	Pathogenic	0.59	D
MetaRNN	Pathogenic	0.99	D;D
MetaSVM	Pathogenic	1.0	D
MutationAssessor	Pathogenic	4.1	.;H
PrimateAI	Pathogenic	0.82	D
PROVEAN	Pathogenic	-8.7	D;D
REVEL	Pathogenic	0.99
Sift	Pathogenic	0.0	D;D
Sift4G	Pathogenic	0.0010	D;D
Polyphen		1.0	.;D
Vest4		0.97
MutPred		0.97		.;Loss of catalytic residue at P113 (P = 0.0824);
MVP		0.98
MPC		0.046
ClinPred		1.0	D
GERP RS		5.4
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.7
Varity_R		0.99
gMVP		0.95

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	0.97
dbscSNV1_RF	Pathogenic	0.89
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: rs104894530; hg19: chr16-8904937;