rs755402538

Variant summary

Our verdict is Likely pathogenic. Variant got 9 ACMG points: 9P and 0B. PM1PM2PP3_StrongPP5

The NM_000303.3(PMM2):c.124G>A(p.Gly42Arg) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.0000155 in 1,612,194 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. 12/21 in silico tools predict a damaging outcome for this variant. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars). Synonymous variant affecting the same amino acid position (i.e. G42G) has been classified as Likely benign.

Frequency

Genomes: 𝑓 0.0000066 ( 0 hom., cov: 33)

Exomes 𝑓: 0.000016 ( 0 hom. )

Consequence

PMM2
NM_000303.3 missense

Scores

Clinical Significance

Conflicting classifications of pathogenicity criteria provided, conflicting classifications P:2U:5

Conservation

PhyloP100: 9.30

Variant links:

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]

PMM2 links:

Genome browser will be placed here

ACMG classification

Classification made for transcript

Verdict is Likely_pathogenic. Variant got 9 ACMG points.

PM1

In a hotspot region, there are 3 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 1 benign, 4 uncertain in NM_000303.3

PM2

Very rare variant in population databases, with high coverage;

PP3

MetaRNN computational evidence supports a deleterious effect, 0.992

PP5

Variant 16-8801856-G-A is Pathogenic according to our data. Variant chr16-8801856-G-A is described in ClinVar as [Conflicting_classifications_of_pathogenicity]. Clinvar id is 555844.We mark this variant Likely_pathogenic, oryginal submissions are: {Uncertain_significance=4, Likely_pathogenic=2}. Variant chr16-8801856-G-A is described in Lovd as [Pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
PMM2	NM_000303.3 linkuse as main transcript	c.124G>A	p.Gly42Arg	missense_variant	2/8	ENST00000268261.9
PMM2	XM_047434215.1 linkuse as main transcript	c.-49G>A		5_prime_UTR_variant	1/6

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
PMM2	ENST00000268261.9 linkuse as main transcript	c.124G>A	p.Gly42Arg	missense_variant	2/8	1	NM_000303.3	P1	O15305-1

Frequencies

GnomAD3 genomes

AF:

0.00000657

AC:

AN:

152104

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.00

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

GnomAD3 exomes

AF:

0.0000200

AC:

AN:

249876

Hom.:

AF XY:

0.0000222

AC XY:

AN XY:

135098

show subpopulations

Gnomad AFR exome

AF:

0.00

Gnomad AMR exome

AF:

0.00

Gnomad ASJ exome

AF:

0.00

Gnomad EAS exome

AF:

0.00

Gnomad SAS exome

AF:

0.0000328

Gnomad FIN exome

AF:

0.00

Gnomad NFE exome

AF:

0.0000355

Gnomad OTH exome

AF:

0.00

GnomAD4 exome

AF:

0.0000164

AC:

AN:

1460090

Hom.:

Cov.:

AF XY:

0.0000220

AC XY:

AN XY:

726296

show subpopulations

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:

0.0000116

Gnomad4 FIN exome

AF:

0.00

Gnomad4 NFE exome

AF:

0.0000198

Gnomad4 OTH exome

AF:

0.0000166

GnomAD4 genome

AF:

0.00000657

AC:

AN:

152104

Hom.:

Cov.:

AF XY:

0.00

AC XY:

AN XY:

74280

show subpopulations

Gnomad4 AFR

AF:

0.00

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:

0.0000147

Gnomad4 OTH

AF:

0.00

Alfa

AF:

0.000178

Hom.:

Bravo

AF:

0.0000113

TwinsUK

AF:

0.000270

AC:

ALSPAC

AF:

0.000259

AC:

ExAC

AF:

0.0000165

AC:

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Pathogenic:2Uncertain:5

Revision: criteria provided, conflicting classifications

LINK: link

Submissions by phenotype

PMM2-congenital disorder of glycosylation

Pathogenic:2Uncertain:3

Uncertain significance, no assertion criteria provided	clinical testing	Natera, Inc.	Sep 16, 2020	- -
Uncertain significance, criteria provided, single submitter	clinical testing	Counsyl	Dec 28, 2017	- -
Likely pathogenic, criteria provided, single submitter	clinical testing	Invitae	Dec 12, 2023	This sequence change replaces glycine, which is neutral and non-polar, with arginine, which is basic and polar, at codon 42 of the PMM2 protein (p.Gly42Arg). This variant is present in population databases (rs755402538, gnomAD 0.003%). This missense change has been observed in individual(s) with congenital disorder of glycosylation type 1a (PMID: 12357336, 15844218). ClinVar contains an entry for this variant (Variation ID: 555844). 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 PMM2 protein function with a positive predictive value of 95%. In summary, the currently available evidence indicates that the variant is pathogenic, but additional data are needed to prove that conclusively. Therefore, this variant has been classified as Likely Pathogenic. -
Likely pathogenic, criteria provided, single submitter	clinical testing	Baylor Genetics	Oct 05, 2023	- -
Uncertain significance, criteria provided, single submitter	clinical testing	Fulgent Genetics, Fulgent Genetics	Feb 16, 2022	- -

not specified

Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Women's Health and Genetics/Laboratory Corporation of America, LabCorp

Jan 28, 2022

Variant summary: PMM2 c.124G>A (p.Gly42Arg) results in a non-conservative amino acid change in the encoded protein sequence. Five of five in-silico tools predict a damaging effect of the variant on protein function. The variant allele was found at a frequency of 2e-05 in 249876 control chromosomes (gnomAD). c.124G>A has been reported in the literature in compound heterozygous individuals affected with Congenital Disorder Of Glycosylation Type 1a (e.g. Schollen_2002, Tiwary_2022). In addition, Le Bizec et al (2005) describe a heterozygote individual with the variant exhibiting intermediate PMM activity. These data indicate that the variant may be associated with disease. Four ClinVar submitters (evaluation after 2014) cite the variant as uncertain significance. Based on the evidence outlined above, the variant was classified as VUS-possibly pathogenic. -

not provided

Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

GeneDx

Sep 08, 2023

Reported heterozygous in an individual with CDG-1A and intermediated phosphomannomutase activity (Le Bizec et al., 2005); Reported in a patient with CDG-1a who also harbored a second missense variant (Schollen et al., 2002); 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; This variant is associated with the following publications: (PMID: 25525159, 15844218, 34426522, 16009061, 32457805, 35281664, 12357336) -

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Pathogenic

0.99

BayesDel_addAF

Pathogenic

0.51

BayesDel_noAF

Pathogenic

0.60

Cadd

Pathogenic

Dann

Pathogenic

1.0

DEOGEN2

Pathogenic

0.93

D;D;.

Eigen

Pathogenic

1.0

Eigen_PC

Pathogenic

0.97

FATHMM_MKL

Pathogenic

0.98

LIST_S2

Pathogenic

1.0

D;D;D

M_CAP

Pathogenic

0.51

MetaRNN

Pathogenic

0.99

D;D;D

MetaSVM

Pathogenic

1.1

MutationTaster

Benign

1.0

D;D;D;D;D

PrimateAI

Uncertain

0.68

PROVEAN

Pathogenic

-6.6

D;D;D

Sift

Pathogenic

0.0

D;D;D

Sift4G

Pathogenic

0.0

D;D;D

Polyphen

1.0

.;D;.

Vest4

0.95

MutPred

0.96

.;Gain of MoRF binding (P = 0.0266);Gain of MoRF binding (P = 0.0266);

MVP

0.98

MPC

0.045

ClinPred

1.0

GERP RS

6.0

RBP_binding_hub_radar

1.0

RBP_regulation_power_radar

2.7

Varity_R

0.98

gMVP

0.97

Splicing

Name

Calibrated prediction

Score

Prediction

SpliceAI score (max)

0.010

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

Below is the list of publications found by LitVar. It may be empty.

Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

ACMG classification

Transcripts

RefSeq

Ensembl

Frequencies

ClinVar

Submissions by phenotype

Computational scores

Splicing

Publications

LitVar

Other links and lift over