rs751986971

chr16-8804788-T-G

Variant summary

Our verdict is Likely pathogenic. Variant got 7 ACMG points: 7P and 0B. PM1 PM2 PM5 PP3

The NM_000303.3(PMM2):c.200T>G(p.Val67Gly) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.000075 in 1,613,116 control chromosomes in the GnomAD database, with no homozygous occurrence. 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. V67M) has been classified as Likely pathogenic.

• Frequency:
  • Genomes: 𝑓 0.000026 (0 hom., cov: 32)
  • Exomes 𝑓: 0.000080 (0 hom.)
• Consequence: PMM2 NM_000303.3 missense
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications P:1 U:3
• Conservation: PhyloP100: 7.49

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 7 ACMG points.

• PM1: In a hotspot region, there are 4 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 0 benign, 3 uncertain in NM_000303.3
• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chrnull-null-null-null is described in UniProt as null.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.812

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
PMM2	NM_000303.3	c.200T>G	p.Val67Gly	missense_variant	3/8	ENST00000268261.9
PMM2	XM_047434215.1	c.7-1528T>G		intron_variant

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
PMM2	ENST00000268261.9	c.200T>G	p.Val67Gly	missense_variant	3/8	1	NM_000303.3	P1

Frequencies

GnomAD3 genomes AF: 0.0000263 AC: 4 AN: 152218 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: 0.0000441

Gnomad OTH AF: 0.00

GnomAD3 exomes AF: 0.0000199 AC: 5 AN: 251388 Hom.: 0 AF XY: 0.0000368 AC XY: 5 AN XY: 135888

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: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.0000440

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.0000801 AC: 117 AN: 1460898 Hom.: 0 Cov.: 29 AF XY: 0.0000839 AC XY: 61 AN XY: 726814

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: 0.000103

Gnomad4 OTH exome AF: 0.0000331

GnomAD4 genome AF: 0.0000263 AC: 4 AN: 152218 Hom.: 0 Cov.: 32 AF XY: 0.0000134 AC XY: 1 AN XY: 74374

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: 0.0000441

Gnomad4 OTH AF: 0.00

Alfa AF: 0.0000502 Hom.: 0

Bravo AF: 0.0000227

ExAC AF: 0.0000165 AC: 2

EpiCase AF: 0.000164

EpiControl AF: 0.00

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Pathogenic:1 Uncertain:3

Revision: criteria provided, conflicting classifications

Submissions by phenotype

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

Uncertain significance, criteria provided, single submitter	clinical testing	Counsyl	Nov 08, 2017	- -
Pathogenic, criteria provided, single submitter	clinical testing	Invitae	Jan 08, 2024	This sequence change replaces valine, which is neutral and non-polar, with glycine, which is neutral and non-polar, at codon 67 of the PMM2 protein (p.Val67Gly). This variant is present in population databases (rs751986971, gnomAD 0.004%). This missense change has been observed in individual(s) with congenital disorder of gylcosylation type Ia (PMID: 16435227). In at least one individual the data is consistent with being in trans (on the opposite chromosome) from a pathogenic variant. ClinVar contains an entry for this variant (Variation ID: 285370). 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%. This variant disrupts the p.Val67 amino acid residue in PMM2. Other variant(s) that disrupt this residue have been observed in individuals with PMM2-related conditions (PMID: 11058896), which suggests that this may be a clinically significant amino acid residue. For these reasons, this variant has been classified as Pathogenic. -

not specified Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

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

Feb 20, 2023

Variant summary: PMM2 c.200T>G (p.Val67Gly) results in a non-conservative amino acid change in the encoded protein sequence. Four 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 251388 control chromosomes. The available data on variant occurrences in the general population are insufficient to allow any conclusion about variant significance. c.200T>G has been reported in the literature in at least one individual affected with Congenital Disorder Of Glycosylation Type 1a. These data do not allow any conclusion about variant significance. To our knowledge, no experimental evidence demonstrating an impact on protein function has been reported. Three clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar after 2014 without evidence for independent evaluation (Pathogenic n=1, VUS n=2). In addition, p.V67M has also been reported to associate with Congenital Disorder Of Glycosylation Type 1a. 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

Eurofins Ntd Llc (ga)

Dec 14, 2015

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.72
BayesDel_addAF	Pathogenic	0.43	D
BayesDel_noAF	Pathogenic	0.51
Cadd	Pathogenic	28
Dann	Uncertain	1.0
DEOGEN2	Pathogenic	0.80	D;D
Eigen	Pathogenic	0.78
Eigen_PC	Pathogenic	0.78
FATHMM_MKL	Pathogenic	0.97	D
LIST_S2	Uncertain	0.94	D;D
M_CAP	Uncertain	0.12	D
MetaRNN	Pathogenic	0.81	D;D
MetaSVM	Pathogenic	1.1	D
MutationTaster	Benign	1.0	D;D;D;D;D
PrimateAI	Uncertain	0.58	T
PROVEAN	Pathogenic	-5.3	D;D
Sift	Benign	0.15	T;T
Sift4G	Benign	0.15	T;T
Polyphen		1.0	.;D
Vest4		0.69
MVP		0.99
MPC		0.041
ClinPred		0.87	D
GERP RS		5.9
Varity_R		0.89
gMVP		0.97

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: rs751986971; hg19: chr16-8898645;