15-74893137-G-A

Variant names:

• chr15-74893137-G-A
• rs759579169
• NM_002435.3:c.488-1G>A

Variant summary

Our verdict is Likely pathogenic. The variant received 7 ACMG points: 7P and 0B. PVS1_Strong PM2 PP5

The NM_002435.3(MPI):​c.488-1G>A variant causes a splice acceptor, intron change involving the alteration of a conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a pathogenic outcome for this variant. 3/3 splice prediction tools predicting alterations to normal splicing. Variant has been reported in ClinVar as Likely pathogenic (no stars).

• Frequency: Genomes: not found (cov: 33)
• Consequence: MPI NM_002435.3 splice_acceptor, intron
• Scores: Splicing: ADA: 1.000
• Clinical Significance: Likely pathogenic no assertion criteria provided P:1
• Conservation: PhyloP100: 9.53
• Publications: 2 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: ClinGen, Myriad Women’s Health, G2P, Orphanet, Labcorp Genetics (formerly Invitae)

ACMG classification

Our verdict: Likely_pathogenic. The variant received 7 ACMG points.

• PVS1: Splicing +-2 bp (donor or acceptor) variant, product NOT destroyed by NMD, known LOF gene, truncates exone, which is 0.14386792 fraction of the gene. Cryptic splice site detected, with MaxEntScore 7.3, offset of 2, new splice context is: ggccttgccttcctgtaaAGgtg. Cryptic site results in frameshift change. If cryptic site found is not functional and variant results in exon loss, it results in inframe change.
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 15-74893137-G-A is Pathogenic according to our data. Variant chr15-74893137-G-A is described in ClinVar as Likely_pathogenic. ClinVar VariationId is 371308.Status of the report is no_assertion_criteria_provided, 0 stars.

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_002435.3. You can select a different transcript below to see updated ACMG assignments.

RefSeq Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	MPI	NM_002435.3	MANE Select	c.488-1G>A		splice_acceptor intron	N/A	NP_002426.1	P34949-1
	MPI	NM_001330372.2		c.428-1G>A		splice_acceptor intron	N/A	NP_001317301.1	H3BPB8
	MPI	NM_001289156.2		c.338-1G>A		splice_acceptor intron	N/A	NP_001276085.1	F5GX71

Ensembl Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	MPI	ENST00000352410.9	TSL:1 MANE Select	c.488-1G>A		splice_acceptor intron	N/A	ENSP00000318318.6	P34949-1
	MPI	ENST00000323744.10	TSL:1	c.487+335G>A		intron	N/A	ENSP00000318192.6	P34949-2
	MPI	ENST00000563422.5	TSL:1	c.488-1G>A		splice_acceptor intron	N/A	ENSP00000457885.1	H3BUZ9

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome Cov.: 31

GnomAD4 genome Cov.: 33

ClinVar

ClinVar submissions

Significance: Likely pathogenic

Revision: no assertion criteria provided

Pathogenic	VUS	Benign	Condition
1	-	-	MPI-congenital disorder of glycosylation (1)

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.60	D
BayesDel_noAF	Pathogenic	0.35
CADD	Pathogenic	35
DANN	Uncertain	0.99
Eigen	Pathogenic	1.1
Eigen_PC	Pathogenic	0.95
FATHMM_MKL	Pathogenic	0.98	D
PhyloP100		9.5
GERP RS		5.4

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	0.93
SpliceAI score (max)		0.99		Details are displayed if max score is > 0.2
DS_AG_spliceai		0.88		Position offset: 3
DS_AL_spliceai		0.99		Position offset: 1

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

Other links and lift over

dbSNP: rs759579169; hg19: chr15-75185478;