Genetic Variant NM_002180.3:c.15T>C (chr11-68903967-T-C) – ACMG Classification: Likely_benign (-3 pts)

Variant summary

Our verdict is Likely benign. The variant received -3 ACMG points: 2P and 5B. PM2BP4_StrongBP7

The NM_002180.3(IGHMBP2):c.15T>C(p.Ala5Ala) variant causes a synonymous change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000071 in 1,407,594 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. No clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar. Synonymous variant affecting the same amino acid position (i.e. A5A) has been classified as Likely benign.

Frequency

Genomes: not found (cov: 35)

Exomes 𝑓: 7.1e-7 ( 0 hom. )

Consequence

IGHMBP2
NM_002180.3 synonymous

Scores

Clinical Significance

Not reported in ClinVar

Conservation

PhyloP100: -4.06

Publications

0 publications found

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:

MRPL21 (HGNC:14479): (mitochondrial ribosomal protein L21) Mammalian mitochondrial ribosomal proteins are encoded by nuclear genes and help in protein synthesis within the mitochondrion. Mitochondrial ribosomes (mitoribosomes) consist of a small 28S subunit and a large 39S subunit. They have an estimated 75% protein to rRNA composition compared to prokaryotic ribosomes, where this ratio is reversed. Another difference between mammalian mitoribosomes and prokaryotic ribosomes is that the latter contain a 5S rRNA. Among different species, the proteins comprising the mitoribosome differ greatly in sequence, and sometimes in biochemical properties, which prevents easy recognition by sequence homology. This gene encodes a 39S subunit protein. Multiple transcript variants encoding different isoforms were identified through sequence analysis although some may be subject to nonsense-mediated decay (NMD). [provided by RefSeq, Jul 2008]

MRPL21 links:

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ACMG classification

Classification was made for transcript

Our verdict: Likely_benign. The variant received -3 ACMG points.

PM2

Very rare variant in population databases, with high coverage;

BP4

Computational evidence support a benign effect (BayesDel_noAF=-0.99).

BP7

Synonymous conserved (PhyloP=-4.06 with no splicing effect.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
IGHMBP2	NM_002180.3 link	c.15T>C	p.Ala5Ala	synonymous_variant	Exon 1 of 15	ENST00000255078.8	NP_002171.2	P38935
MRPL21	NM_181514.2 link	c.-157A>G		upstream_gene_variant		ENST00000362034.7	NP_852615.1	Q7Z2W9-1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
IGHMBP2	ENST00000255078.8 link	c.15T>C	p.Ala5Ala	synonymous_variant	Exon 1 of 15	1	NM_002180.3	ENSP00000255078.4		P38935
MRPL21	ENST00000362034.7 link	c.-157A>G		upstream_gene_variant		1	NM_181514.2	ENSP00000354580.2		Q7Z2W9-1

Frequencies

GnomAD3 genomes

Cov.:

GnomAD4 exome

AF:

7.10e-7

AC:

AN:

1407594

Hom.:

Cov.:

AF XY:

0.00000144

AC XY:

AN XY:

695656

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:

31940

American (AMR)

AF:

0.00

AC:

AN:

36360

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

25244

East Asian (EAS)

AF:

0.00

AC:

AN:

36360

South Asian (SAS)

AF:

0.00

AC:

AN:

81016

European-Finnish (FIN)

AF:

0.00

AC:

AN:

48598

Middle Eastern (MID)

AF:

0.00

AC:

AN:

5690

European-Non Finnish (NFE)

AF:

9.22e-7

AC:

AN:

1084078

Other (OTH)

AF:

0.00

AC:

AN:

58308

⚠️ 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: 0.225

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

BayesDel_noAF

Benign

-0.99

CADD

Benign

0.66

(source)

DANN

Benign

0.73

PhyloP100

-4.1

PromoterAI

0.019

Neutral

(source)

RBP_binding_hub_radar

0.0

RBP_regulation_power_radar

1.6

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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NM_002180.3:c.15T>C

Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

Publications

ACMG classification

Transcripts

RefSeq

Ensembl

Frequencies

Age Distribution

ClinVar

Computational scores

Splicing

Publications

Other links and lift over