chr16-8811700-C-CA

Position:

• chr16-8811700-C-CA

Variant summary

Our verdict is Pathogenic. Variant got 18 ACMG points: 18P and 0B. PVS1 PM2 PP5_Very_Strong

The NM_000303.3(PMM2):​c.511dupA​(p.Thr171fs) variant causes a frameshift change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000206 in 1,456,924 control chromosomes in the GnomAD database, with no homozygous occurrence. Variant has been reported in ClinVar as Likely pathogenic (★★). Variant results in nonsense mediated mRNA decay.

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 0.0000021 (0 hom.)
• Consequence: PMM2 NM_000303.3 frameshift
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:3
• Conservation: PhyloP100: 2.46

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 18 ACMG points.

• PVS1: Loss of function variant, product undergoes nonsense mediated mRNA decay. LoF is a known mechanism of disease.
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 16-8811700-C-CA is Pathogenic according to our data. Variant chr16-8811700-C-CA is described in ClinVar as [Likely_pathogenic]. Clinvar id is 370217.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
PMM2	NM_000303.3	c.511dupA	p.Thr171fs	frameshift_variant	6/8	ENST00000268261.9	NP_000294.1
PMM2	XM_047434215.1	c.262dupA	p.Thr88fs	frameshift_variant	4/6		XP_047290171.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
PMM2	ENST00000268261.9	c.511dupA	p.Thr171fs	frameshift_variant	6/8	1	NM_000303.3	ENSP00000268261.4

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome AF: 0.00000206 AC: 3 AN: 1456924 Hom.: 0 Cov.: 29 AF XY: 0.00000276 AC XY: 2 AN XY: 725152

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: 0.00000271

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 33

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:3

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

PMM2-congenital disorder of glycosylation Pathogenic:2

Likely pathogenic, criteria provided, single submitter	clinical testing	Counsyl	Dec 15, 2015	- -
Pathogenic, criteria provided, single submitter	clinical testing	Labcorp Genetics (formerly Invitae), Labcorp	Oct 05, 2023	This sequence change creates a premature translational stop signal (p.Thr171Asnfs*11) in the PMM2 gene. It is expected to result in an absent or disrupted protein product. Loss-of-function variants in PMM2 are known to be pathogenic (PMID: 19862844). This variant is not present in population databases (gnomAD no frequency). This premature translational stop signal has been observed in individual(s) with mild clinical features of PMM2-congenital disorders of glycosylation (PMID: 25355454). ClinVar contains an entry for this variant (Variation ID: 370217). For these reasons, this variant has been classified as Pathogenic. -

See cases Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Laboratorio de Genetica e Diagnostico Molecular, Hospital Israelita Albert Einstein

Nov 07, 2019

ACMG classification criteria: PVS1, PS4, PM2, PM3 -

Computational scores

Source: dbNSFP v4.3

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: rs1057516323; hg19: chr16-8905557;