NM_000528.4:c.1259G>T

Variant names:

Variant summary

Our verdict is Uncertain significance. The variant received 4 ACMG points: 4P and 0B. PM2PP3PP5

The NM_000528.4(MAN2B1):c.1259G>T(p.Gly420Val) variant causes a missense change. The variant allele was found at a frequency of 0.00000682 in 1,613,386 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 Conflicting classifications of pathogenicity (no stars). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. G420D) has been classified as Uncertain significance.

Frequency

Genomes: 𝑓 0.000013 ( 0 hom., cov: 32)

Exomes 𝑓: 0.0000062 ( 0 hom. )

Consequence

MAN2B1
NM_000528.4 missense

Scores

Clinical Significance

Conflicting classifications of pathogenicity criteria provided, conflicting classifications P:1U:4

Conservation

PhyloP100: 4.58

Publications

3 publications found

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 Gene-Disease associations (from GenCC):

alpha-mannosidosis
Inheritance: AR Classification: DEFINITIVE, STRONG Submitted by: ClinGen, Genomics England PanelApp, Myriad Women’s Health, G2P, Laboratory for Molecular Medicine, Labcorp Genetics (formerly Invitae)

MAN2B1 links:

Genome browser will be placed here

ACMG classification

Classification was made for transcript

Our verdict: Uncertain_significance. The variant received 4 ACMG points.

PM2

Very rare variant in population databases, with high coverage;

PP3

MetaRNN computational evidence supports a deleterious effect, 0.838

PP5

Variant 19-12658113-C-A is Pathogenic according to our data. Variant chr19-12658113-C-A is described in ClinVar as Conflicting_classifications_of_pathogenicity. ClinVar VariationId is 208264.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
MAN2B1	NM_000528.4 link	c.1259G>T	p.Gly420Val	missense_variant	Exon 10 of 24	ENST00000456935.7	NP_000519.2	O00754-1
MAN2B1	NM_001440570.1 link	c.1262G>T	p.Gly421Val	missense_variant	Exon 10 of 24		NP_001427499.1
MAN2B1	NM_001173498.2 link	c.1256G>T	p.Gly419Val	missense_variant	Exon 10 of 24		NP_001166969.1	O00754-2A8K6A7
MAN2B1	XM_047438841.1 link	c.158G>T	p.Gly53Val	missense_variant	Exon 3 of 17		XP_047294797.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
MAN2B1	ENST00000456935.7 link	c.1259G>T	p.Gly420Val	missense_variant	Exon 10 of 24	1	NM_000528.4	ENSP00000395473.2		O00754-1

Frequencies

GnomAD3 genomes

AF:

0.0000131

AC:

AN:

152170

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.0000241

Gnomad AMI

AF:

0.00

Gnomad AMR

AF:

0.0000655

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

GnomAD2 exomes

AF:

0.0000120

AC:

AN:

249208

AF XY:

0.00

show subpopulations

Gnomad AFR exome

AF:

0.00

Gnomad AMR exome

AF:

0.0000579

Gnomad ASJ exome

AF:

0.00

Gnomad EAS exome

AF:

0.00

Gnomad FIN exome

AF:

0.00

Gnomad NFE exome

AF:

0.00

Gnomad OTH exome

AF:

0.000164

GnomAD4 exome

AF:

0.00000616

AC:

AN:

1461216

Hom.:

Cov.:

AF XY:

0.00000688

AC XY:

AN XY:

726916

show subpopulations

African (AFR)

AF:

0.00

AC:

AN:

33480

American (AMR)

AF:

0.0000894

AC:

AN:

44724

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

26136

East Asian (EAS)

AF:

0.00

AC:

AN:

39698

South Asian (SAS)

AF:

0.00

AC:

AN:

86258

European-Finnish (FIN)

AF:

0.00

AC:

AN:

52802

Middle Eastern (MID)

AF:

0.00

AC:

AN:

5746

European-Non Finnish (NFE)

AF:

0.00000360

AC:

AN:

1111990

Other (OTH)

AF:

0.0000166

AC:

AN:

60382

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.503

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Age Distribution

Exome Het

Variant carriers

<30

30-35

35-40

40-45

45-50

50-55

55-60

60-65

65-70

70-75

75-80

>80

Age

GnomAD4 genome

AF:

0.0000131

AC:

AN:

152170

Hom.:

Cov.:

AF XY:

0.00

AC XY:

AN XY:

74324

show subpopulations

African (AFR)

AF:

0.0000241

AC:

AN:

41452

American (AMR)

AF:

0.0000655

AC:

AN:

15278

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

3472

East Asian (EAS)

AF:

0.00

AC:

AN:

5196

South Asian (SAS)

AF:

0.00

AC:

AN:

4832

European-Finnish (FIN)

AF:

0.00

AC:

AN:

10610

Middle Eastern (MID)

AF:

0.00

AC:

AN:

316

European-Non Finnish (NFE)

AF:

0.00

AC:

AN:

68010

Other (OTH)

AF:

0.00

AC:

AN:

2092

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.450

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Age Distribution

Genome Het

Variant carriers

<30

30-35

35-40

40-45

45-50

50-55

55-60

60-65

65-70

70-75

75-80

>80

Age

Alfa

AF:

0.00

Hom.:

Bravo

AF:

0.0000113

ExAC

AF:

0.0000165

AC:

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Pathogenic:1Uncertain:4

Revision: criteria provided, conflicting classifications

LINK: link

Submissions by phenotype

Deficiency of alpha-mannosidase

Pathogenic:1Uncertain:3

Jul 26, 2023

Baylor Genetics

Significance:Likely pathogenic

Review Status:criteria provided, single submitter

Collection Method:clinical testing

- -

Jun 07, 2012

ClinVar Staff, National Center for Biotechnology Information (NCBI)

Significance:Uncertain significance

Review Status:no assertion criteria provided

Collection Method:literature only

- -

May 07, 2022

Fulgent Genetics, Fulgent Genetics

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

- -

Oct 22, 2022

Labcorp Genetics (formerly Invitae), Labcorp

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

This sequence change replaces glycine, which is neutral and non-polar, with valine, which is neutral and non-polar, at codon 420 of the MAN2B1 protein (p.Gly420Val). This variant is present in population databases (rs772853856, gnomAD 0.01%). This missense change has been observed in individual(s) with leukodystrophy (PMID: 17404523). ClinVar contains an entry for this variant (Variation ID: 208264). Advanced modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) performed at Invitae indicates that this missense variant is not expected to disrupt MAN2B1 protein function. Experimental studies have shown that this missense change affects MAN2B1 function (PMID: 21505070, 22161967). In summary, the available evidence is currently insufficient to determine the role of this variant in disease. Therefore, it has been classified as a Variant of Uncertain Significance. -

not specified

Uncertain:1

Jun 06, 2025

Women's Health and Genetics/Laboratory Corporation of America, LabCorp

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

Variant summary: MAN2B1 c.1259G>T (p.Gly420Val) results in a non-conservative amino acid change in the encoded protein sequence. Algorithms developed to predict the effect of missense changes on protein structure and function all suggest that this variant is likely to be disruptive. The variant allele was found at a frequency of 1.2e-05 in 249208 control chromosomes. c.1259G>T has been observed in an individual affected with leukodystrophy who had reduced alpha-mannosidosis activity (Castelnovo_2007). This report does not provide unequivocal conclusions about association of the variant with Deficiency of alpha-mannosidase. Experimental studies evaluating an impact on protein function have reported that the variant is processed into a peptide that localizes to the lysosome, but is not secreted, resulting in <20% of WT activity (e.g. Kuokkanen_2011, Riise Stensland_2012). The following publications have been ascertained in the context of this evaluation (PMID: 17404523, 21505070, 22161967). ClinVar contains an entry for this variant (Variation ID: 208264). Based on the evidence outlined above, the variant was classified as VUS-possibly pathogenic. -

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Uncertain

0.52

BayesDel_addAF

Pathogenic

0.19

BayesDel_noAF

Pathogenic

0.26

CADD

Uncertain

(source)

DANN

Uncertain

0.99

DEOGEN2

Uncertain

0.64

D;.

Eigen

Uncertain

0.36

Eigen_PC

Uncertain

0.40

FATHMM_MKL

Uncertain

0.94

LIST_S2

Benign

0.79

T;T

M_CAP

Pathogenic

0.34

MetaRNN

Pathogenic

0.84

D;D

MetaSVM

Uncertain

0.021

MutationAssessor

Benign

1.6

L;.

PhyloP100

4.6

PrimateAI

Uncertain

0.63

PROVEAN

Uncertain

-4.3

D;D

REVEL

Pathogenic

0.72

Sift

Benign

0.035

D;D

Sift4G

Uncertain

0.044

D;D

Polyphen

0.70

P;.

Vest4

0.61

MutPred

0.63

Gain of stability (P = 0.0508);.;

MVP

0.90

MPC

1.4

ClinPred

0.86

GERP RS

5.0

RBP_binding_hub_radar

0.0

RBP_regulation_power_radar

1.7

Varity_R

0.71

gMVP

0.81

Mutation Taster

=3/97

disease causing

(source)

Splicing

Name

Calibrated prediction

Score

Prediction

SpliceAI score (max)

0.010

Details are displayed if max score is > 0.2

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

Publications

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Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

Publications

ACMG classification

Transcripts

RefSeq

Ensembl

Frequencies

Age Distribution

Age Distribution

ClinVar

Submissions by phenotype

Computational scores

Splicing

Publications

Other links and lift over