Genetic Variant MAN1B1:p.Arg334Cys (chr9-137101088-C-T) – ACMG Classification: Pathogenic (13 pts)

Variant summary

Our verdict is Pathogenic. The variant received 13 ACMG points: 13P and 0B. PS3PM2PM5PP3_StrongPP5

The NM_016219.5(MAN1B1):c.1000C>T(p.Arg334Cys) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.0000229 in 1,614,132 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. 14/22 in silico tools predict a damaging outcome for this variant. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars). ClinVar reports functional evidence for this variant: "SCV000914282: Expression of wild type and p.Arg334Cys variant constructs in HEK293 cells showed that the variant protein was expressed and secreted at 20% of the wild type levels, with a reduction in the kinetic efficiency of the enzyme compared to wild type (Rafiq et al. 2011)." and additional evidence is available in ClinVar. Another variant affecting the same amino acid position, but resulting in a different missense (i.e. R334H) has been classified as Likely pathogenic.

Frequency

Genomes: 𝑓 0.000059 ( 0 hom., cov: 33)

Exomes 𝑓: 0.000019 ( 0 hom. )

Consequence

MAN1B1
NM_016219.5 missense

Scores

Clinical Significance

Conflicting classifications of pathogenicity criteria provided, conflicting classifications P:8U:1

Conservation

PhyloP100: 7.68

Publications

15 publications found

Variant links:

Genes affected

MAN1B1 (HGNC:6823): (mannosidase alpha class 1B member 1) This gene encodes an enzyme belonging to the glycosyl hydrolase 47 family. This enzyme functions in N-glycan biosynthesis, and is a class I alpha-1,2-mannosidase that specifically converts Man9GlcNAc to Man8GlcNAc isomer B. It is required for N-glycan trimming to Man5-6GlcNAc2 in the endoplasmic-reticulum-associated degradation pathway. Mutations in this gene cause autosomal-recessive intellectual disability. Alternative splicing results in multiple transcript variants. A related pseudogene has been identified on chromosome 11. [provided by RefSeq, Dec 2011]

MAN1B1 Gene-Disease associations (from GenCC):

MAN1B1-congenital disorder of glycosylation
Inheritance: AR Classification: DEFINITIVE, SUPPORTIVE Submitted by: ClinGen, Orphanet
Rafiq syndrome
Inheritance: AR Classification: DEFINITIVE, STRONG Submitted by: Ambry Genetics, Labcorp Genetics (formerly Invitae), G2P
autosomal recessive non-syndromic intellectual disability
Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet

MAN1B1 links:

Genome browser will be placed here

ACMG classification

Classification was made for transcript

Our verdict: Pathogenic. The variant received 13 ACMG points.

PS3

PS3 evidence extracted from ClinVar submissions: SCV000914282: Expression of wild type and p.Arg334Cys variant constructs in HEK293 cells showed that the variant protein was expressed and secreted at 20% of the wild type levels, with a reduction in the kinetic efficiency of the enzyme compared to wild type (Rafiq et al. 2011).; SCV002640297: Studies in HEK293 cells showed decreased expression of the variant protein and reduction in kinetic efficiency of the enzyme compared to wild type, while studies in patient derived fibroblasts indicated this alteration would lead to reduced protein expression, N-Glycan abnormalities, and altered Golgi morphology (Rafiq, 2011; Rymen, 2013).

PM2

Very rare variant in population databases, with high coverage;

PM5

Other missense variant is known to change same aminoacid residue: Variant chr9-137101089-G-A is described in ClinVar as Conflicting_classifications_of_pathogenicity. ClinVar VariationId is 1218674.

PP3

MetaRNN computational evidence supports a deleterious effect, 0.981

PP5

Variant 9-137101088-C-T is Pathogenic according to our data. Variant chr9-137101088-C-T is described in ClinVar as Conflicting_classifications_of_pathogenicity. ClinVar VariationId is 30415.

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_016219.5. You can select a different transcript below to see updated ACMG assignments.

RefSeq Transcripts

Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
MAN1B1	NM_016219.5	MANE Select	c.1000C>T	p.Arg334Cys	missense	Exon 7 of 13	NP_057303.2	Q9UKM7
MAN1B1	NR_045720.2		n.1015C>T		non_coding_transcript_exon	Exon 7 of 13
MAN1B1	NR_045721.2		n.1146C>T		non_coding_transcript_exon	Exon 8 of 14

Ensembl Transcripts

Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
MAN1B1	ENST00000371589.9	TSL:1 MANE Select	c.1000C>T	p.Arg334Cys	missense	Exon 7 of 13	ENSP00000360645.4	Q9UKM7
MAN1B1	ENST00000371587.9	TSL:1	n.*702C>T		non_coding_transcript_exon	Exon 8 of 14	ENSP00000483132.2	A0A087X064
MAN1B1	ENST00000544448.6	TSL:1	n.1000C>T		non_coding_transcript_exon	Exon 7 of 13	ENSP00000444966.2	H0YGV7

Frequencies

GnomAD3 genomes

AF:

0.0000591

AC:

AN:

152186

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.0000965

Gnomad AMI

AF:

0.00

Gnomad AMR

AF:

0.000196

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:

0.000478

GnomAD2 exomes

AF:

0.0000358

AC:

AN:

251440

AF XY:

0.0000147

show subpopulations

Gnomad AFR exome

AF:

0.000185

Gnomad AMR exome

AF:

0.0000578

Gnomad ASJ exome

AF:

0.00

Gnomad EAS exome

AF:

0.00

Gnomad FIN exome

AF:

0.00

Gnomad NFE exome

AF:

0.0000264

Gnomad OTH exome

AF:

0.00

GnomAD4 exome

AF:

0.0000192

AC:

AN:

1461828

Hom.:

Cov.:

AF XY:

0.0000179

AC XY:

AN XY:

727216

show subpopulations

African (AFR)

AF:

0.000119

AC:

AN:

33480

American (AMR)

AF:

0.0000224

AC:

AN:

44724

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

26136

East Asian (EAS)

AF:

0.00

AC:

AN:

39700

South Asian (SAS)

AF:

0.0000116

AC:

AN:

86258

European-Finnish (FIN)

AF:

0.00

AC:

AN:

53374

Middle Eastern (MID)

AF:

0.00

AC:

AN:

5764

European-Non Finnish (NFE)

AF:

0.0000180

AC:

AN:

1111998

Other (OTH)

AF:

0.0000331

AC:

AN:

60394

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.473

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:

0.0000591

AC:

AN:

152304

Hom.:

Cov.:

AF XY:

0.0000269

AC XY:

AN XY:

74460

show subpopulations

African (AFR)

AF:

0.0000962

AC:

AN:

41566

American (AMR)

AF:

0.000196

AC:

AN:

15298

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

3472

East Asian (EAS)

AF:

0.00

AC:

AN:

5190

South Asian (SAS)

AF:

0.00

AC:

AN:

4818

European-Finnish (FIN)

AF:

0.00

AC:

AN:

10608

Middle Eastern (MID)

AF:

0.00

AC:

AN:

294

European-Non Finnish (NFE)

AF:

0.0000147

AC:

AN:

68030

Other (OTH)

AF:

0.000473

AC:

AN:

2116

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.508

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:

0.0000266

Hom.:

Bravo

AF:

0.0000378

ExAC

AF:

0.0000494

AC:

ClinVar

ClinVar submissions

Significance:Conflicting classifications of pathogenicity

Revision:criteria provided, conflicting classifications

View on ClinVar

Pathogenic

VUS

Benign

Condition

Rafiq syndrome (5)

Inborn genetic diseases (1)

MAN1B1-related disorder (1)

not provided (1)

See cases (1)

Computational scores

Source: dbNSFP v4.9

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Pathogenic

0.91

BayesDel_addAF

Pathogenic

0.27

BayesDel_noAF

Pathogenic

0.43

CADD

Pathogenic

(source)

DANN

Pathogenic

1.0

DEOGEN2

Pathogenic

0.82

Eigen

Pathogenic

0.97

Eigen_PC

Pathogenic

0.85

FATHMM_MKL

Pathogenic

0.99

LIST_S2

Pathogenic

1.0

M_CAP

Pathogenic

0.53

MetaRNN

Pathogenic

0.98

MetaSVM

Pathogenic

1.1

MutationAssessor

Pathogenic

4.1

PhyloP100

7.7

PrimateAI

Pathogenic

0.84

PROVEAN

Pathogenic

-7.4

REVEL

Pathogenic

0.94

Sift

Pathogenic

0.0

Sift4G

Pathogenic

0.0

Polyphen

1.0

Vest4

1.0

MutPred

0.90

Gain of catalytic residue at F329 (P = 0.1623)

MVP

0.98

MPC

0.51

ClinPred

1.0

GERP RS

5.7

RBP_binding_hub_radar

0.0

RBP_regulation_power_radar

1.7

Varity_R

0.97

gMVP

0.97

Mutation Taster

=0/100

disease causing (ClinVar)

(source)

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

Publications

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Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

Publications

ACMG classification

Variant Effect in Transcripts

RefSeq Transcripts

Ensembl Transcripts

Frequencies

Age Distribution

Age Distribution

ClinVar

Computational scores

Splicing

Publications

Other links and lift over