rs104894532

Positions:

• chr16-8797908-G-A
• chr16-8797908-G-T

Variant summary

Our verdict is Pathogenic. Variant got 16 ACMG points: 16P and 0B. PM1 PM2 PP3_Strong PP5_Very_Strong

The NM_000303.3(PMM2):​c.26G>A​(p.Cys9Tyr) variant causes a missense change. The variant allele was found at a frequency of 0.00000206 in 1,458,958 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 Likely pathogenic (★★).

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 0.0000021 (0 hom.)
• Consequence: PMM2 NM_000303.3 missense
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:5
• Conservation: PhyloP100: 6.86

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 (HGNC:):

ACMG classification

Verdict is Pathogenic. Variant got 16 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: MetaRNN computational evidence supports a deleterious effect, 0.966
• PP5: Variant 16-8797908-G-A is Pathogenic according to our data. Variant chr16-8797908-G-A is described in ClinVar as [Likely_pathogenic]. Clinvar id is 7720.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars. Variant chr16-8797908-G-A is described in Lovd as [Pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
PMM2	NM_000303.3	c.26G>A	p.Cys9Tyr	missense_variant	1/8	ENST00000268261.9	NP_000294.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
PMM2	ENST00000268261.9	c.26G>A	p.Cys9Tyr	missense_variant	1/8	1	NM_000303.3	ENSP00000268261.4

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD3 exomes AF: 0.00000415 AC: 1 AN: 241228 Hom.: 0 AF XY: 0.00000760 AC XY: 1 AN XY: 131550

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: 0.00000919

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000206 AC: 3 AN: 1458958 Hom.: 0 Cov.: 32 AF XY: 0.00000413 AC XY: 3 AN XY: 725624

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: 0.00000270

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 33

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:5

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

PMM2-congenital disorder of glycosylation Pathogenic:5

Pathogenic, criteria provided, single submitter	clinical testing	Labcorp Genetics (formerly Invitae), Labcorp	Jul 22, 2023	For these reasons, this variant has been classified as Pathogenic. Experimental studies have shown that this missense change affects PMM2 function (PMID: 10922383, 11715002). 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. ClinVar contains an entry for this variant (Variation ID: 7720). This missense change has been observed in individual(s) with congenital disorder of glycosylation type 1a (PMID: 10922383, 11715002). In at least one individual the data is consistent with being in trans (on the opposite chromosome) from a pathogenic variant. This variant is present in population databases (rs104894532, gnomAD 0.0009%). This sequence change replaces cysteine, which is neutral and slightly polar, with tyrosine, which is neutral and polar, at codon 9 of the PMM2 protein (p.Cys9Tyr). -
Pathogenic, no assertion criteria provided	literature only	OMIM	Aug 01, 2000	- -
Pathogenic, criteria provided, single submitter	clinical testing	Baylor Genetics	Aug 12, 2022	- -
Likely pathogenic, criteria provided, single submitter	literature only	Counsyl	Aug 27, 2014	- -
Pathogenic, criteria provided, single submitter	clinical testing	Women's Health and Genetics/Laboratory Corporation of America, LabCorp	Apr 23, 2018	Variant summary: PMM2 c.26G>A (p.Cys9Tyr) 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 was observed with an allele frequency of 4.2e-06 in 236634 control chromosomes (gnomAD and publications). The variant, c.26G>A, has been reported in the literature in multiple individuals affected with Congenital Disorder of Glycosylation Type 1a (Bjursell_2000, Vuillaumier-Barrot_2000). These data indicate that the variant is very likely to be associated with disease. At least one publication reports experimental evidence evaluating an impact on protein function. The most pronounced variant effect results in 30%-50% of normal activity. No clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar after 2014. Based on the evidence outlined above, the variant was classified as pathogenic. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.86
BayesDel_addAF	Pathogenic	0.53	D
BayesDel_noAF	Pathogenic	0.52
CADD	Pathogenic	27
DANN	Uncertain	0.99
DEOGEN2	Pathogenic	0.86	D;.
Eigen	Uncertain	0.46
Eigen_PC	Uncertain	0.51
FATHMM_MKL	Uncertain	0.94	D
LIST_S2	Uncertain	0.93	D;D
M_CAP	Uncertain	0.21	D
MetaRNN	Pathogenic	0.97	D;D
MetaSVM	Pathogenic	1.1	D
MutationAssessor	Uncertain	2.3	M;.
PrimateAI	Pathogenic	0.88	D
PROVEAN	Pathogenic	-5.5	D;D
REVEL	Pathogenic	0.89
Sift	Uncertain	0.0020	D;D
Sift4G	Uncertain	0.0030	D;D
Polyphen		0.37	B;.
Vest4		0.87
MutPred		0.88		Loss of catalytic residue at L10 (P = 0.0407);Loss of catalytic residue at L10 (P = 0.0407);
MVP		0.99
MPC		0.0087
ClinPred		0.99	D
GERP RS		4.8
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.7
Varity_R		0.95
gMVP		0.93

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: rs104894532; hg19: chr16-8891765;