Genetic Variant NM_002180.3:c.1516G>T (chr11-68933892-G-T) – ACMG Classification: Pathogenic (12 pts)

Variant summary

Our verdict is Pathogenic. The variant received 12 ACMG points: 12P and 0B. PVS1PM2PP5_Moderate

The NM_002180.3(IGHMBP2):c.1516G>T(p.Glu506*) variant causes a stop gained change. The variant allele was found at a frequency of 0.000000692 in 1,444,206 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 Pathogenic (★). Synonymous variant affecting the same amino acid position (i.e. E506E) has been classified as Likely benign. Variant results in nonsense mediated mRNA decay.

Frequency

Genomes: not found (cov: 33)

Exomes 𝑓: 6.9e-7 ( 0 hom. )

Consequence

IGHMBP2
NM_002180.3 stop_gained

Scores

Clinical Significance

Pathogenic criteria provided, single submitter P:1

Conservation

PhyloP100: 6.97

Variant links:

Genes affected

IGHMBP2 (HGNC:5542): (immunoglobulin mu DNA binding protein 2) This gene encodes a helicase superfamily member that binds a specific DNA sequence from the immunoglobulin mu chain switch region. Mutations in this gene lead to spinal muscle atrophy with respiratory distress type 1. [provided by RefSeq, Jul 2008]

IGHMBP2 links:

Genome browser will be placed here

ACMG classification

Classification was made for transcript

Our verdict: Pathogenic. The variant received 12 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 11-68933892-G-T is Pathogenic according to our data. Variant chr11-68933892-G-T is described in ClinVar as [Pathogenic]. Clinvar id is 574350.Status of the report is criteria_provided_single_submitter, 1 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
IGHMBP2	NM_002180.3 link	c.1516G>T	p.Glu506*	stop_gained	Exon 10 of 15	ENST00000255078.8	NP_002171.2	P38935

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
IGHMBP2	ENST00000255078.8 link	c.1516G>T	p.Glu506*	stop_gained	Exon 10 of 15	1	NM_002180.3	ENSP00000255078.4		P38935

Frequencies

GnomAD3 genomes

Cov.:

GnomAD4 exome

AF:

6.92e-7

AC:

AN:

1444206

Hom.:

Cov.:

AF XY:

0.00000139

AC XY:

AN XY:

716844

show subpopulations

⚠️ The allele balance in gnomAD version 4 Exomes is significantly skewed from the expected value of 0.5.

African (AFR)

AF:

0.00

AC:

AN:

33192

American (AMR)

AF:

0.00

AC:

AN:

42112

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

25776

East Asian (EAS)

AF:

0.00

AC:

AN:

39142

South Asian (SAS)

AF:

0.0000119

AC:

AN:

83746

European-Finnish (FIN)

AF:

0.00

AC:

AN:

52320

Middle Eastern (MID)

AF:

0.00

AC:

AN:

5740

European-Non Finnish (NFE)

AF:

0.00

AC:

AN:

1102508

Other (OTH)

AF:

0.00

AC:

AN:

59670

⚠️ The allele balance in gnomAD4 Exomes is highly skewed from 0.5 (p-value = 0.000000), which strongly suggests a high chance of mosaicism in these individuals.

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.275

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

GnomAD4 genome

Cov.:

Alfa

AF:

0.00

Hom.:

Bravo

AF:

0.00000378

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:1

Revision: criteria provided, single submitter

LINK: link

Submissions by phenotype

Autosomal recessive distal spinal muscular atrophy 1;C4015349:Charcot-Marie-Tooth disease axonal type 2S

Pathogenic:1

May 23, 2019

Labcorp Genetics (formerly Invitae), Labcorp

Significance:Pathogenic

Review Status:criteria provided, single submitter

Collection Method:clinical testing

For these reasons, this variant has been classified as Pathogenic. Loss-of-function variants in IGHMBP2 are known to be pathogenic (PMID: 14681881, 25439726, 25568292). This variant has not been reported in the literature in individuals with IGHMBP2-related disease. This variant is not present in population databases (ExAC no frequency). This sequence change creates a premature translational stop signal (p.Glu506*) in the IGHMBP2 gene. It is expected to result in an absent or disrupted protein product. -

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

BayesDel_addAF

Pathogenic

0.63

BayesDel_noAF

Pathogenic

0.62

CADD

Pathogenic

(source)

DANN

Uncertain

0.99

Eigen

Uncertain

0.57

Eigen_PC

Uncertain

0.28

FATHMM_MKL

Pathogenic

0.98

PhyloP100

7.0

Vest4

0.74

GERP RS

3.7

Mutation Taster

=2/198

disease causing (ClinVar)

(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

ACMG classification

Transcripts

RefSeq

Ensembl

Frequencies

ClinVar

Submissions by phenotype

Computational scores

Splicing

Publications

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