15-74890080-GCT-G

Variant names:

• chr15-74890080-GCT-G
• NM_002435.3:c.9_10delTC

Variant summary

Our verdict is Pathogenic. The variant received 12 ACMG points: 12P and 0B. PVS1 PM2 PP5_Moderate

The NM_002435.3(MPI):​c.9_10delTC​(p.Pro4AlafsTer31) variant causes a frameshift change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000137 in 1,455,404 control chromosomes in the GnomAD database, with no homozygous occurrence. Variant has been reported in ClinVar as Pathogenic (★).

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000014 (0 hom.)
• Consequence: MPI NM_002435.3 frameshift
• Clinical Significance: Pathogenic criteria provided, single submitter P:1
• Conservation: PhyloP100: 0.149
• Publications: 0 publications found

Genes affected

MPI (HGNC:7216): (mannose phosphate isomerase) Phosphomannose isomerase catalyzes the interconversion of fructose-6-phosphate and mannose-6-phosphate and plays a critical role in maintaining the supply of D-mannose derivatives, which are required for most glycosylation reactions. Mutations in the MPI gene were found in patients with carbohydrate-deficient glycoprotein syndrome, type Ib. Alternative splicing results in multiple transcript variants. [provided by RefSeq, Jan 2014]

MPI Gene-Disease associations (from GenCC):

• MPI-congenital disorder of glycosylation

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

ACMG classification

Our verdict: Pathogenic. The variant received 12 ACMG points.

• PVS1: Loss of function variant, product does not undergo nonsense mediated mRNA decay. Variant located near the start codon (<100nt), not predicted to undergo nonsense mediated mRNA decay. There are 113 pathogenic variants in the truncated region.
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 15-74890080-GCT-G is Pathogenic according to our data. Variant chr15-74890080-GCT-G is described in ClinVar as [Pathogenic]. Clinvar id is 3680466.Status of the report is criteria_provided_single_submitter, 1 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
MPI	NM_002435.3	c.9_10delTC	p.Pro4AlafsTer31	frameshift_variant	Exon 1 of 8	ENST00000352410.9	NP_002426.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
MPI	ENST00000352410.9	c.9_10delTC	p.Pro4AlafsTer31	frameshift_variant	Exon 1 of 8	1	NM_002435.3	ENSP00000318318.6

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 0.00000137 AC: 2 AN: 1455404 Hom.: 0 AF XY: 0.00000138 AC XY: 1 AN XY: 724368

African (AFR) AF: 0.00 AC: 0 AN: 33466

American (AMR) AF: 0.00 AC: 0 AN: 44714

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26122

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: 47294

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5614

European-Non Finnish (NFE) AF: 0.00 AC: 0 AN: 1111928

Other (OTH) AF: 0.0000331 AC: 2 AN: 60338

GnomAD4 genome Cov.: 32

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:1

Revision: criteria provided, single submitter

Submissions by phenotype

MPI-congenital disorder of glycosylation Pathogenic:1

Mar 06, 2024

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change creates a premature translational stop signal (p.Pro4Alafs*31) in the MPI gene. It is expected to result in an absent or disrupted protein product. Loss-of-function variants in MPI are known to be pathogenic (PMID: 19862844). This variant is not present in population databases (gnomAD no frequency). This variant has not been reported in the literature in individuals affected with MPI-related conditions. For these reasons, this variant has been classified as Pathogenic. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
PhyloP100		0.15

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

hg19: chr15-75182421;