Genetic Variant MAN1B1:p.Ala27ProfsTer34 (chr9-137087074-CGG-C) – ACMG Classification: Pathogenic (10 pts)

Variant summary

Our verdict is Pathogenic. The variant received 10 ACMG points: 10P and 0B. PVS1PM2

The NM_016219.5(MAN1B1):c.78_79delGG(p.Ala27ProfsTer34) variant causes a frameshift change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000000689 in 1,450,440 control chromosomes in the GnomAD database, with no homozygous occurrence. No clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar. Synonymous variant affecting the same amino acid position (i.e. G26G) has been classified as Likely benign.

Frequency

Genomes: not found (cov: 34)

Exomes 𝑓: 6.9e-7 ( 0 hom. )

Consequence

MAN1B1
NM_016219.5 frameshift

Scores

Not classified

Clinical Significance

Not reported in ClinVar

Conservation

PhyloP100: 0.413

Publications

0 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: Orphanet, ClinGen
Rafiq syndrome
Inheritance: AR Classification: DEFINITIVE, STRONG Submitted by: G2P, PanelApp Australia, Labcorp Genetics (formerly Invitae), Ambry Genetics
autosomal recessive non-syndromic intellectual disability
Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet

MAN1B1 links:

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ACMG classification

Classification was made for transcript

Our verdict: Pathogenic. The variant received 10 ACMG points.

PVS1

Loss of function variant, product does not undergo nonsense mediated mRNA decay. Variant located near the start codon (<100nt), not predicted to undergo nonsense mediated mRNA decay. There are 48 pathogenic variants in the truncated region.

PM2

Very rare variant in population databases, with high coverage;

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
MAN1B1	NM_016219.5 link	c.78_79delGG	p.Ala27ProfsTer34	frameshift_variant	Exon 1 of 13	ENST00000371589.9	NP_057303.2	Q9UKM7
MAN1B1	XM_006716945.5 link	c.78_79delGG	p.Ala27ProfsTer34	frameshift_variant	Exon 1 of 12		XP_006717008.1	H0YG20
MAN1B1	NR_045720.2 link	n.93_94delGG		non_coding_transcript_exon_variant	Exon 1 of 13
MAN1B1	NR_045721.2 link	n.93_94delGG		non_coding_transcript_exon_variant	Exon 1 of 14

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
MAN1B1	ENST00000371589.9 link	c.78_79delGG	p.Ala27ProfsTer34	frameshift_variant	Exon 1 of 13	1	NM_016219.5	ENSP00000360645.4		Q9UKM7

Frequencies

GnomAD3 genomes

Cov.:

GnomAD4 exome

AF:

6.89e-7

AC:

AN:

1450440

Hom.:

AF XY:

0.00000139

AC XY:

AN XY:

720578

show subpopulations

African (AFR)

AF:

0.00

AC:

AN:

33404

American (AMR)

AF:

0.00

AC:

AN:

43126

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

25654

East Asian (EAS)

AF:

0.00

AC:

AN:

39314

South Asian (SAS)

AF:

0.00

AC:

AN:

84238

European-Finnish (FIN)

AF:

0.0000197

AC:

AN:

50752

Middle Eastern (MID)

AF:

0.00

AC:

AN:

5672

European-Non Finnish (NFE)

AF:

0.00

AC:

AN:

1108392

Other (OTH)

AF:

0.00

AC:

AN:

59888

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.475

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

GnomAD4 genome

Cov.:

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

PhyloP100

0.41

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

Transcripts

RefSeq

Ensembl

Frequencies

ClinVar

Computational scores

Splicing

Publications

Other links and lift over