rs1555449795

Variant names:

• chr16-8813017-C-A
• rs1555449795
• NM_000303.3:c.550C>A

Your query was ambiguous. Multiple possible variants found:

• chr16-8813017-C-A
• chr16-8813017-C-G

Variant summary

Our verdict is Pathogenic. The variant received 10 ACMG points: 10P and 0B. PM1 PM2 PP2 PP3_Strong PP5

The NM_000303.3(PMM2):​c.550C>A​(p.Pro184Thr) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000137 in 1,460,774 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). Synonymous variant affecting the same amino acid position (i.e. P184P) has been classified as Likely benign.

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 0.0000014 (0 hom.)
• Consequence: PMM2 NM_000303.3 missense
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications P:1 U:3
• Conservation: PhyloP100: 7.48
• Publications: 1 publications found

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 Gene-Disease associations (from GenCC):

• congenital disorder of glycosylation type I

  Inheritance: AR Classification: DEFINITIVE Submitted by: Myriad Women’s Health
• PMM2-congenital disorder of glycosylation

  Inheritance: AR Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: G2P, Labcorp Genetics (formerly Invitae), Orphanet, PanelApp Australia, ClinGen

ACMG classification

Our verdict: Pathogenic. The variant received 10 ACMG points.

• PM1: In a hotspot region, there are 8 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 0 benign, 6 uncertain in NM_000303.3
• PM2: Very rare variant in population databases, with high coverage
• PP2: Missense variant in the gene, where a lot of missense mutations are associated with disease in ClinVar. The gene has 89 curated pathogenic missense variants (we use a threshold of 10). The gene has 24 curated benign missense variants. Gene score misZ: -1.3872 (below the threshold of 3.09). Trascript score misZ: -1.8083 (below the threshold of 3.09). GenCC associations: The gene is linked to PMM2-congenital disorder of glycosylation, congenital disorder of glycosylation type I.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.991
• PP5: Variant 16-8813017-C-A is Pathogenic according to our data. Variant chr16-8813017-C-A is described in ClinVar as [Conflicting_classifications_of_pathogenicity]. Clinvar id is 551026.We mark this variant Likely_pathogenic, oryginal submission is: [Conflicting_classifications_of_pathogenicity].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
PMM2	NM_000303.3	c.550C>A	p.Pro184Thr	missense_variant	Exon 7 of 8	ENST00000268261.9	NP_000294.1
PMM2	XM_047434215.1	c.301C>A	p.Pro101Thr	missense_variant	Exon 5 of 6		XP_047290171.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
PMM2	ENST00000268261.9	c.550C>A	p.Pro184Thr	missense_variant	Exon 7 of 8	1	NM_000303.3	ENSP00000268261.4

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome AF: 0.00000137 AC: 2 AN: 1460774 Hom.: 0 Cov.: 30 AF XY: 0.00000138 AC XY: 1 AN XY: 726774

African (AFR) AF: 0.00 AC: 0 AN: 33464

American (AMR) AF: 0.00 AC: 0 AN: 44722

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26128

East Asian (EAS) AF: 0.00 AC: 0 AN: 39696

South Asian (SAS) AF: 0.00 AC: 0 AN: 86232

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53416

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5766

European-Non Finnish (NFE) AF: 0.00000180 AC: 2 AN: 1110984

Other (OTH) AF: 0.00 AC: 0 AN: 60366

GnomAD4 genome Cov.: 33

Alfa AF: 0.00 Hom.: 0

Bravo AF: 0.00000378

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:2

Feb 23, 2023

3billion

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The variant is not observed in the gnomAD v2.1.1 dataset. Functional studies provide moderate evidence of the variant having a damaging effect on the gene or gene product (PMID: 21541725). In silico tool predictions suggest damaging effect of the variant on gene or gene product (REVEL: 0.95; 3Cnet: 0.80). Same nucleotide change resulting in same amino acid change has been previously reported to be associated with PMM2 related disorder (PMID: 21541725). Therefore, this variant is classified as Likely pathogenic according to the recommendation of ACMG/AMP guideline. -

Mar 15, 2017

Counsyl

Significance: Uncertain significance

Review Status: no assertion criteria provided

Collection Method: clinical testing

This submission and the accompanying classification are no longer maintained by the submitter. For more information on current observations and classification, please contact variantquestions@myriad.com. -

Sep 01, 2021

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change replaces proline with threonine at codon 184 of the PMM2 protein (p.Pro184Thr). The proline residue is highly conserved and there is a small physicochemical difference between proline and threonine. This variant is not present in population databases (ExAC no frequency). This missense change has been observed in individual(s) with PMM2-CDG (PMID: 21541725). ClinVar contains an entry for this variant (Variation ID: 551026). 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. Experimental studies have shown that this missense change affects PMM2 function (PMID: 21541725). 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. -

not specified Uncertain:1

Sep 11, 2024

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

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Variant summary: PMM2 c.550C>A (p.Pro184Thr) 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 absent in 251486 control chromosomes. c.550C>A has been reported in the literature in individuals affected with Congenital Disorder Of Glycosylation Type 1a who also carried another variant, c.353C>G, in cis (e.g. Vega_2011, Perez-Cerda_2017, Morena-Barrio_2016, Quelhas_2021). These report(s) do not provide unequivocal conclusions about association of the variant with Congenital Disorder Of Glycosylation Type 1a. At least one publication reports experimental evidence evaluating an impact on protein function. The most pronounced variant effect results in 1% of normal phosphomannomutase activity (Vega_2011). The following publications have been ascertained in the context of this evaluation (PMID: 27214821, 28139241, 33340551, 21541725). ClinVar contains an entry for this variant (Variation ID: 551026). Based on the evidence outlined above, the variant was classified as VUS-possibly pathogenic. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.93
BayesDel_addAF	Pathogenic	0.57	D
BayesDel_noAF	Pathogenic	0.59
CADD	Pathogenic	29
DANN	Uncertain	1.0
DEOGEN2	Pathogenic	0.93	D;D;.
Eigen	Pathogenic	0.87
Eigen_PC	Pathogenic	0.79
FATHMM_MKL	Uncertain	0.96	D
LIST_S2	Pathogenic	1.0	D;D;D
M_CAP	Pathogenic	0.72	D
MetaRNN	Pathogenic	0.99	D;D;D
MetaSVM	Pathogenic	1.0	D
MutationAssessor	Pathogenic	4.1	.;H;.
PhyloP100		7.5
PrimateAI	Uncertain	0.69	T
PROVEAN	Pathogenic	-7.7	D;D;D
REVEL	Pathogenic	0.95
Sift	Pathogenic	0.0	D;D;D
Sift4G	Pathogenic	0.0	D;D;D
Polyphen		1.0	.;D;.
Vest4		0.96
MutPred		0.90		.;Loss of sheet (P = 0.0817);.;
MVP		0.98
MPC		0.046
ClinPred		1.0	D
GERP RS		4.8
RBP_binding_hub_radar		0.92
RBP_regulation_power_radar		2.6
Varity_R		0.97
gMVP		0.91
Mutation Taster		=0/100	disease causing

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: rs1555449795; hg19: chr16-8906874;