chr19-12649418-G-A

Position:

chr19-12649418-G-A

Variant summary

Our verdict is Pathogenic. Variant got 18 ACMG points: 18P and 0B. PVS1PM2PP5_Very_Strong

The NM_000528.4(MAN2B1):c.2278C>T(p.Arg760Ter) variant causes a stop gained change. The variant allele was found at a frequency of 0.00000621 in 1,610,244 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Likely pathogenic (★★). Synonymous variant affecting the same amino acid position (i.e. R760R) has been classified as Likely benign. Variant results in nonsense mediated mRNA decay.

Frequency

Genomes: 𝑓 0.000020 ( 0 hom., cov: 31)

Exomes 𝑓: 0.0000048 ( 0 hom. )

Consequence

MAN2B1
NM_000528.4 stop_gained

Scores

Clinical Significance

Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:7

Conservation

PhyloP100: 3.91

Variant links:

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]

MAN2B1 links:

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ACMG classification

Classification made for transcript

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 19-12649418-G-A is Pathogenic according to our data. Variant chr19-12649418-G-A is described in ClinVar as [Likely_pathogenic]. Clinvar id is 1685.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE
MAN2B1	NM_000528.4 linkuse as main transcript	c.2278C>T	p.Arg760Ter	stop_gained	19/24	ENST00000456935.7
MAN2B1	NM_001173498.2 linkuse as main transcript	c.2275C>T	p.Arg759Ter	stop_gained	19/24
MAN2B1	XM_005259913.3 linkuse as main transcript	c.2281C>T	p.Arg761Ter	stop_gained	19/24
MAN2B1	XM_047438841.1 linkuse as main transcript	c.1177C>T	p.Arg393Ter	stop_gained	12/17

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
MAN2B1	ENST00000456935.7 linkuse as main transcript	c.2278C>T	p.Arg760Ter	stop_gained	19/24	1	NM_000528.4	A1	O00754-1
MAN2B1	ENST00000221363.8 linkuse as main transcript	c.2275C>T	p.Arg759Ter	stop_gained	19/24	1		P4	O00754-2
MAN2B1	ENST00000466794.5 linkuse as main transcript	n.2868C>T		non_coding_transcript_exon_variant	17/22	2

Frequencies

GnomAD3 genomes

AF:

0.0000198

AC:

AN:

151274

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.0000730

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:

0.00

Gnomad OTH

AF:

0.00

GnomAD3 exomes

AF:

0.0000121

AC:

AN:

248886

Hom.:

AF XY:

0.0000149

AC XY:

AN XY:

134638

show subpopulations

Gnomad AFR exome

AF:

0.000125

Gnomad AMR exome

AF:

0.00

Gnomad ASJ exome

AF:

0.00

Gnomad EAS exome

AF:

0.00

Gnomad SAS exome

AF:

0.0000329

Gnomad FIN exome

AF:

0.00

Gnomad NFE exome

AF:

0.00

Gnomad OTH exome

AF:

0.00

GnomAD4 exome

AF:

0.00000480

AC:

AN:

1458970

Hom.:

Cov.:

AF XY:

0.00000827

AC XY:

AN XY:

725800

show subpopulations

Gnomad4 AFR exome

AF:

0.00

Gnomad4 AMR exome

AF:

0.00

Gnomad4 ASJ exome

AF:

0.00

Gnomad4 EAS exome

AF:

0.0000253

Gnomad4 SAS exome

AF:

0.0000232

Gnomad4 FIN exome

AF:

0.00

Gnomad4 NFE exome

AF:

0.00000360

Gnomad4 OTH exome

AF:

0.00

GnomAD4 genome

AF:

0.0000198

AC:

AN:

151274

Hom.:

Cov.:

AF XY:

0.0000271

AC XY:

AN XY:

73842

show subpopulations

Gnomad4 AFR

AF:

0.0000730

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:

0.00

Gnomad4 OTH

AF:

0.00

Alfa

AF:

0.0000688

Hom.:

Bravo

AF:

0.0000113

ExAC

AF:

0.0000247

AC:

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:7

Revision: criteria provided, multiple submitters, no conflicts

LINK: link

Submissions by phenotype

Deficiency of alpha-mannosidase

Pathogenic:7

Pathogenic, no assertion criteria provided	clinical testing	Natera, Inc.	Sep 16, 2020	- -
Pathogenic, criteria provided, single submitter	clinical testing	Baylor Genetics	Aug 09, 2023	- -
Likely pathogenic, criteria provided, single submitter	literature only	Counsyl	Jul 30, 2014	- -
Pathogenic, no assertion criteria provided	literature only	OMIM	Oct 01, 1998	- -
Pathogenic, criteria provided, single submitter	clinical testing	Genome-Nilou Lab	Sep 05, 2021	- -
Pathogenic, criteria provided, single submitter	clinical testing	Labcorp Genetics (formerly Invitae), Labcorp	Jan 16, 2024	This sequence change creates a premature translational stop signal (p.Arg760*) in the MAN2B1 gene. It is expected to result in an absent or disrupted protein product. Loss-of-function variants in MAN2B1 are known to be pathogenic (PMID: 9915946, 22161967). The frequency data for this variant in the population databases is considered unreliable, as metrics indicate poor data quality at this position in the gnomAD database. This premature translational stop signal has been observed in individual(s) with clinical features of mannosidosis (PMID: 9758606). ClinVar contains an entry for this variant (Variation ID: 1685). Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant may disrupt the consensus splice site. For these reasons, this variant has been classified as Pathogenic. -
Pathogenic, criteria provided, single submitter	clinical testing	Women's Health and Genetics/Laboratory Corporation of America, LabCorp	Mar 02, 2017	Variant summary: The MAN2B1 c.2278C>T (p.Arg760X) variant results in a premature termination codon, predicted to cause a truncated or absent MAN2B1 protein due to nonsense mediated decay, which are commonly known mechanisms for disease. The variant of interest was observed in the large, broad control population, ExAC, with an allele frequency of 2/108116 (1/54058), which does not exceed the estimated maximal expected allele frequency for a pathogenic MAN2B1 variant of 1/632. A publication, Godota_1998, cites the variant in a sibling pair, where both sisters were homozygous for the variant. Authors indicate that the variant causes a Lysosomal alpha-mannosidosis type 2, with a milder phenotype, hypothesized by "The nonsense mutation in the alpha-mannosidase gene is located in exon 19, at a point ~75% along the length of the protein. This nonsense mutation likely encodes an unstable mRNA, such that a relatively stable but defective protein is produced that can show partial activity toward alpha-mannose residues in vivo." In addition, multiple clinical diagnostic laboratories/reputable databases classified this variant as likely pathogenic/pathogenic. Taken together, this variant is classified as pathogenic. -

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

BayesDel_addAF

Pathogenic

0.63

BayesDel_noAF

Pathogenic

0.50

CADD

Pathogenic

DANN

Uncertain

1.0

Eigen

Uncertain

0.45

Eigen_PC

Benign

0.22

FATHMM_MKL

Uncertain

0.95

MutationTaster

Benign

1.0

A;A

Vest4

0.34

GERP RS

2.3

Splicing

Name

Calibrated prediction

Score

Prediction

SpliceAI score (max)

0.080

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

Below is the list of publications found by LitVar. It may be empty.

Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

ACMG classification

Transcripts

RefSeq

Ensembl

Frequencies

ClinVar

Submissions by phenotype

Computational scores

Splicing

Publications

LitVar

Other links and lift over