rs1555453238

Positions:

• chr16-8847724-G-A

Variant summary

Our verdict is Likely pathogenic. Variant got 9 ACMG points: 9P and 0B. PM1 PM2 PP3_Strong PP5

The NM_000303.3(PMM2):​c.640G>A​(p.Gly214Ser) variant causes a missense, splice region change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000274 in 1,458,594 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic 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: 32)
  • Exomes 𝑓: 0.0000027 (0 hom.)
• Consequence: PMM2 NM_000303.3 missense, splice_region
• Scores: Splicing: ADA: 0.9987
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications P:4 U:1
• Conservation: PhyloP100: 8.29

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 Likely_pathogenic. Variant got 9 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, 0.992
• PP5: Variant 16-8847724-G-A is Pathogenic according to our data. Variant chr16-8847724-G-A is described in ClinVar as [Conflicting_classifications_of_pathogenicity]. Clinvar id is 553503.We mark this variant Likely_pathogenic, oryginal submissions are: {Uncertain_significance=1, Pathogenic=3, Likely_pathogenic=1}. Variant chr16-8847724-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.640G>A	p.Gly214Ser	missense_variant, splice_region_variant	8/8	ENST00000268261.9	NP_000294.1
PMM2	XM_047434215.1	c.391G>A	p.Gly131Ser	missense_variant, splice_region_variant	6/6		XP_047290171.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
PMM2	ENST00000268261.9	c.640G>A	p.Gly214Ser	missense_variant, splice_region_variant	8/8	1	NM_000303.3	ENSP00000268261.4

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 0.00000274 AC: 4 AN: 1458594 Hom.: 0 Cov.: 30 AF XY: 0.00000413 AC XY: 3 AN XY: 725814

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: 0.00000361

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 32

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Pathogenic:4 Uncertain:1

Revision: criteria provided, conflicting classifications

Submissions by phenotype

PMM2-congenital disorder of glycosylation Pathogenic:3 Uncertain:1

Pathogenic, criteria provided, single submitter	clinical testing	Labcorp Genetics (formerly Invitae), Labcorp	Aug 10, 2023	ClinVar contains an entry for this variant (Variation ID: 553503). An algorithm developed to predict the effect of missense changes on protein structure and function (PolyPhen-2) suggests 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 disrupt the consensus splice site. This variant disrupts the p.Gly214 amino acid residue in PMM2. Other variant(s) that disrupt this residue have been observed in individuals with PMM2-related conditions (PMID: 30687093), which suggests that this may be a clinically significant amino acid residue. For these reasons, this variant has been classified as Pathogenic. This missense change has been observed in individual(s) with congenital disorder of glycosylation type 1a (PMID: 12357336, 25497157, 28807751). This sequence change replaces glycine, which is neutral and non-polar, with serine, which is neutral and polar, at codon 214 of the PMM2 protein (p.Gly214Ser). This variant is not present in population databases (gnomAD no frequency). -
Uncertain significance, criteria provided, single submitter	clinical testing	Counsyl	Aug 22, 2017	- -
Pathogenic, criteria provided, single submitter	clinical testing	Mendelics	May 28, 2019	- -
Pathogenic, criteria provided, single submitter	clinical testing	Centre for Mendelian Genomics, University Medical Centre Ljubljana	Mar 30, 2020	This variant was classified as: Pathogenic. The following ACMG criteria were applied in classifying this variant: PS1,PM1,PM2,PP2,PP3,PP5. -

not provided Pathogenic:1

Likely pathogenic, criteria provided, single submitter

clinical testing

GeneDx

May 17, 2024

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; In silico analysis is inconclusive as to whether the variant alters gene splicing. In the absence of RNA/functional studies, the actual effect of this sequence change is unknown.; This variant is associated with the following publications: (PMID: 12357336, 28807751) -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.63
BayesDel_addAF	Pathogenic	0.57	D
BayesDel_noAF	Pathogenic	0.59
CADD	Pathogenic	33
DANN	Uncertain	1.0
DEOGEN2	Pathogenic	0.93	D;D;.
Eigen	Pathogenic	0.83
Eigen_PC	Pathogenic	0.76
FATHMM_MKL	Pathogenic	0.97	D
LIST_S2	Uncertain	0.94	D;D;D
M_CAP	Pathogenic	0.66	D
MetaRNN	Pathogenic	0.99	D;D;D
MetaSVM	Pathogenic	1.0	D
MutationAssessor	Pathogenic	4.1	.;H;.
PrimateAI	Uncertain	0.57	T
PROVEAN	Pathogenic	-5.7	D;D;D
REVEL	Pathogenic	0.98
Sift	Uncertain	0.0010	D;D;D
Sift4G	Uncertain	0.0020	D;D;D
Polyphen		0.99	.;D;.
Vest4		0.97
MutPred		0.93		.;Gain of glycosylation at G214 (P = 0.0158);.;
MVP		0.97
MPC		0.032
ClinPred		1.0	D
GERP RS		5.2
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.7
Varity_R		0.95
gMVP		0.88

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	0.92
SpliceAI score (max)		0.22		Details are displayed if max score is > 0.2
DS_AL_spliceai		0.22		Position offset: 0

Find out detailed SpliceAI scores and Pangolin per-transcript scores at spliceailookup.broadinstitute.org

Publications

LitVar

Other links and lift over

dbSNP: rs1555453238; hg19: chr16-8941581; COSMIC: COSV51634307; COSMIC: COSV51634307;