rs80338678

chr19-12652462-T-C

Variant summary

Our verdict is Pathogenic. Variant got 22 ACMG points: 22P and 0B. PVS1 PM2 PP3_Strong PP5_Very_Strong

The NM_000528.4(MAN2B1):c.1831-2A>G variant causes a splice acceptor change. The variant allele was found at a frequency of 0.00000658 in 152,088 control chromosomes in the GnomAD database, with no homozygous occurrence. 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 Pathogenic (★★).

• Frequency: Genomes: 𝑓 0.0000066 (0 hom., cov: 32)
• Consequence: MAN2B1 NM_000528.4 splice_acceptor
• Scores: Splicing: ADA: 1.000
• Clinical Significance: Pathogenic criteria provided, multiple submitters, no conflicts P:3 O:1
• Conservation: PhyloP100: 5.12

Genes affected

MAN2B1 (HGNC:6826): (mannosidase alpha class 2B member 1) This gene encodes an enzyme that hydrolyzes terminal, non-reducing alpha-D-mannose residues in alpha-D-mannosides. Its activity is necessary for the catabolism of N-linked carbohydrates released during glycoprotein turnover and it is member of family 38 of glycosyl hydrolases. The full length protein is processed in two steps. First, a 49 aa leader sequence is cleaved off and the remainder of the protein is processed into 3 peptides of 70 kDa, 42 kDa (D) and 13/15 kDa (E). Next, the 70 kDa peptide is further processed into three peptides (A, B and C). The A, B and C peptides are disulfide-linked. Defects in this gene have been associated with lysosomal alpha-mannosidosis. Alternatively spliced transcript variants encoding different isoforms have been found for this gene.[provided by RefSeq, Mar 2010]

ACMG classification

Verdict is Pathogenic. Variant got 22 ACMG points.

• PVS1: Splicing variant, LoF is a know mechanism of disease, Cryptic splice site detected, with MaxEntScore 4.8, offset of 31, new splice context is: aacgtttgatcctgacacAGggc. Cryptic site results in frameshift change. If cryptic site found is not functional and variant results in exon loss, it results in frameshift change.
• PM2: Very rare variant in population databases, with high coverage
• PP3: Splicing scoreres supports a deletorius effect: Scorers claiming Pathogenic: dbscSNV1_ADA, dbscSNV1_RF, max_spliceai. No scorers claiming Uncertain. No scorers claiming Benign.
• PP5: Variant 19-12652462-T-C is Pathogenic according to our data. Variant chr19-12652462-T-C is described in ClinVar as [Pathogenic]. Clinvar id is 21208.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
MAN2B1	NM_000528.4	c.1831-2A>G		splice_acceptor_variant		ENST00000456935.7
MAN2B1	NM_001173498.2	c.1828-2A>G		splice_acceptor_variant
MAN2B1	XM_005259913.3	c.1834-2A>G		splice_acceptor_variant
MAN2B1	XM_047438841.1	c.730-2A>G		splice_acceptor_variant

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
MAN2B1	ENST00000456935.7	c.1831-2A>G		splice_acceptor_variant		1	NM_000528.4	A1

Frequencies

GnomAD3 genomes AF: 0.00000658 AC: 1 AN: 152088 Hom.: 0 Cov.: 32

Gnomad AFR AF: 0.00

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.00

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.00

Gnomad SAS AF: 0.00

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.0000147

Gnomad OTH AF: 0.00

GnomAD4 exome Cov.: 31

GnomAD4 genome AF: 0.00000658 AC: 1 AN: 152088 Hom.: 0 Cov.: 32 AF XY: 0.0000135 AC XY: 1 AN XY: 74304

Gnomad4 AFR AF: 0.00

Gnomad4 AMR AF: 0.00

Gnomad4 ASJ AF: 0.00

Gnomad4 EAS AF: 0.00

Gnomad4 SAS AF: 0.00

Gnomad4 FIN AF: 0.00

Gnomad4 NFE AF: 0.0000147

Gnomad4 OTH AF: 0.00

Bravo AF: 0.00000378

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:3 Other:1

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Deficiency of alpha-mannosidase Pathogenic:3 Other:1

Pathogenic, criteria provided, single submitter	clinical testing	Invitae	Mar 31, 2022	For these reasons, this variant has been classified as Pathogenic. Studies have shown that disruption of this splice site results in skipping part of exon 15 and introduces a premature termination codon (PMID: 9915946). The resulting mRNA is expected to undergo nonsense-mediated decay. ClinVar contains an entry for this variant (Variation ID: 21208). This variant is also known as IVS14-2A>G. Disruption of this splice site has been observed in individual(s) with mannosidosis (PMID: 9915946). It has also been observed to segregate with disease in related individuals. This variant is not present in population databases (gnomAD no frequency). This sequence change affects an acceptor splice site in intron 14 of the MAN2B1 gene. RNA analysis indicates that disruption of this splice site induces altered splicing and may result in an absent or disrupted protein product. -
Pathogenic, criteria provided, single submitter	clinical testing	Genome-Nilou Lab	Sep 05, 2021	- -
Pathogenic, criteria provided, single submitter	clinical testing	Counsyl	Sep 22, 2016	- -
not provided, no classification provided	literature only	GeneReviews	-	- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.63	D
BayesDel_noAF	Uncertain	0.070
Cadd	Pathogenic	29
Dann	Uncertain	0.99
Eigen	Pathogenic	0.97
Eigen_PC	Pathogenic	0.78
FATHMM_MKL	Pathogenic	0.97	D
MutationTaster	Benign	1.0	A;A
GERP RS		5.6

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	0.92
SpliceAI score (max)		0.95		Details are displayed if max score is > 0.2
DS_AG_spliceai		0.35		Position offset: -33
DS_AL_spliceai		0.95		Position offset: -2

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

Publications

LitVar

Other links and lift over

dbSNP: rs80338678; hg19: chr19-12763276;