19-12646529-G-A

Variant summary

Our verdict is Likely benign. Variant got -5 ACMG points: 0P and 5B. BP4_Strong BS1_Supporting

The NM_000528.4(MAN2B1):c.*91C>T variant causes a 3 prime UTR change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000596 in 1,007,482 control chromosomes in the GnomAD database, including 2 homozygotes. In-silico tool predicts a benign outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★).

• Frequency:
  • Genomes: 𝑓 0.00024 (0 hom., cov: 31)
  • Exomes 𝑓: 0.00066 (2 hom.)
• Consequence: MAN2B1 NM_000528.4 3_prime_UTR
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 0.453

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 Likely_benign. Variant got -5 ACMG points.

• BP4: Computational evidence support a benign effect (BayesDel_noAF=-0.88).
• BS1: Variant frequency is greater than expected in population eas. gnomad4 allele frequency = 0.000243 (37/152242) while in subpopulation EAS AF= 0.00483 (25/5174). AF 95% confidence interval is 0.00336. There are 0 homozygotes in gnomad4. There are 18 alleles in male gnomad4 subpopulation. Median coverage is 31. This position pass quality control queck. Existence of Clinvar submissions makes me limit the strength of this signal to Supporting

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
MAN2B1	NM_000528.4	c.*91C>T		3_prime_UTR_variant	24/24	ENST00000456935.7
MAN2B1	NM_001173498.2	c.*91C>T		3_prime_UTR_variant	24/24
MAN2B1	XM_005259913.3	c.*91C>T		3_prime_UTR_variant	24/24
MAN2B1	XM_047438841.1	c.*91C>T		3_prime_UTR_variant	17/17

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
MAN2B1	ENST00000456935.7	c.*91C>T		3_prime_UTR_variant	24/24	1	NM_000528.4	A1

Frequencies

GnomAD3 genomes AF: 0.000243 AC: 37 AN: 152124 Hom.: 0 Cov.: 31

Gnomad AFR AF: 0.0000966

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.000262

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.00482

Gnomad SAS AF: 0.00

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.0000441

Gnomad OTH AF: 0.000478

GnomAD4 exome AF: 0.000658 AC: 563 AN: 855240 Hom.: 2 Cov.: 12 AF XY: 0.000616 AC XY: 275 AN XY: 446492

Gnomad4 AFR exome AF: 0.0000461

Gnomad4 AMR exome AF: 0.000128

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.0145

Gnomad4 SAS exome AF: 0.0000553

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.0000370

Gnomad4 OTH exome AF: 0.000124

GnomAD4 genome AF: 0.000243 AC: 37 AN: 152242 Hom.: 0 Cov.: 31 AF XY: 0.000242 AC XY: 18 AN XY: 74434

Gnomad4 AFR AF: 0.0000963

Gnomad4 AMR AF: 0.000262

Gnomad4 ASJ AF: 0.00

Gnomad4 EAS AF: 0.00483

Gnomad4 SAS AF: 0.00

Gnomad4 FIN AF: 0.00

Gnomad4 NFE AF: 0.0000441

Gnomad4 OTH AF: 0.000473

Alfa AF: 0.0000693 Hom.: 0

Bravo AF: 0.000181

Asia WGS AF: 0.00346 AC: 12 AN: 3478

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Deficiency of alpha-mannosidase Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Illumina Laboratory Services, Illumina

Jan 13, 2018

This variant was observed in the ICSL laboratory as part of a predisposition screen in an ostensibly healthy population. It had not been previously curated by ICSL or reported in the Human Gene Mutation Database (HGMD: prior to June 1st, 2018), and was therefore a candidate for classification through an automated scoring system. Utilizing variant allele frequency, disease prevalence and penetrance estimates, and inheritance mode, an automated score was calculated to assess if this variant is too frequent to cause the disease. Based on the score, this variant could not be ruled out of causing disease and therefore its association with disease required further investigation. A literature search was performed for the gene, cDNA change, and amino acid change (if applicable). No publications were found based on this search. This variant was therefore classified as a variant of unknown significance for this disease. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.88
Cadd	Benign	7.4
Dann	Benign	0.74

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.070		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

Other links and lift over

dbSNP: rs145108101; hg19: chr19-12757343;