rs879253887

Positions:

• chr11-68934542-C-T

Variant summary

Our verdict is Pathogenic. Variant got 12 ACMG points: 12P and 0B. PM2 PP3_Moderate PP5_Very_Strong

The NM_002180.3(IGHMBP2):​c.1616C>T​(p.Ser539Leu) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000685 in 1,459,420 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 Likely pathogenic (★★).

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 0.0000069 (0 hom.)
• Consequence: IGHMBP2 NM_002180.3 missense
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:3
• Conservation: PhyloP100: 7.57

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 (HGNC:):

ACMG classification

Verdict is Pathogenic. Variant got 12 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.866
• PP5: Variant 11-68934542-C-T is Pathogenic according to our data. Variant chr11-68934542-C-T is described in ClinVar as [Likely_pathogenic]. Clinvar id is 245629.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
IGHMBP2	NM_002180.3	c.1616C>T	p.Ser539Leu	missense_variant	11/15	ENST00000255078.8	NP_002171.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
IGHMBP2	ENST00000255078.8	c.1616C>T	p.Ser539Leu	missense_variant	11/15	1	NM_002180.3	ENSP00000255078.4

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD3 exomes AF: 0.00000407 AC: 1 AN: 245892 Hom.: 0 AF XY: 0.00000752 AC XY: 1 AN XY: 133066

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.00

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad SAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00000902

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000685 AC: 10 AN: 1459420 Hom.: 0 Cov.: 31 AF XY: 0.00000413 AC XY: 3 AN XY: 725838

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.0000252

Gnomad4 SAS exome AF: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00000540

Gnomad4 OTH exome AF: 0.0000497

GnomAD4 genome Cov.: 33

Bravo AF: 0.00000378

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:3

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

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

Pathogenic, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Aug 30, 2023

This missense change has been observed in individual(s) with clinical features of autosomal recessive distal hereditary motor neuropathy and/or spinal muscular atrophy with respiratory distress type 1 (SMARD1) (PMID: 30598237; Invitae). In at least one individual the data is consistent with being in trans (on the opposite chromosome) from a pathogenic variant. This sequence change replaces serine, which is neutral and polar, with leucine, which is neutral and non-polar, at codon 539 of the IGHMBP2 protein (p.Ser539Leu). The frequency data for this variant in the population databases is considered unreliable, as metrics indicate poor data quality at this position in the gnomAD database. ClinVar contains an entry for this variant (Variation ID: 245629). Advanced modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) has been performed at Invitae for this missense variant, however the output from this modeling did not meet the statistical confidence thresholds required to predict the impact of this variant on IGHMBP2 protein function. For these reasons, this variant has been classified as Pathogenic. -

Autosomal recessive distal spinal muscular atrophy 1 Pathogenic:1

Likely pathogenic, criteria provided, single submitter

clinical testing

Service de Pédiatrie - Neurologie et infectiologie - Toulouse, CHU de Toulouse - Hôpital des Enfants

Aug 17, 2016

6 typical cases of SMARD1 were observed with an homozygous mutation at this location. Although it is a missense mutation on a poorly conserved portion of DNA across species, it involves the main functional domain of the protein IGHMBP 2 the DNA helicase domain, on a specific region where ATP binding sites seems to be concentrated (region 2A). -

not provided Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

GeneDx

Oct 06, 2020

Not observed at a significant frequency in large population cohorts (Lek et al., 2016); In silico analysis supports that this missense variant does not alter protein structure/function; This variant is associated with the following publications: (PMID: 30598237) -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Uncertain	0.42
BayesDel_addAF	Pathogenic	0.23	D
BayesDel_noAF	Uncertain	0.090
CADD	Uncertain	24
DANN	Uncertain	1.0
DEOGEN2	Pathogenic	0.89	D
Eigen	Uncertain	0.51
Eigen_PC	Uncertain	0.45
FATHMM_MKL	Uncertain	0.97	D
LIST_S2	Uncertain	0.97	D
M_CAP	Pathogenic	0.31	D
MetaRNN	Pathogenic	0.87	D
MetaSVM	Pathogenic	0.94	D
MutationAssessor	Pathogenic	3.7	H
PrimateAI	Benign	0.39	T
PROVEAN	Uncertain	-2.5	N
REVEL	Pathogenic	0.67
Sift	Uncertain	0.0070	D
Sift4G	Uncertain	0.0040	D
Polyphen		0.81	P
Vest4		0.50
MutPred		0.76		Gain of loop (P = 0.0851);
MVP		0.98
MPC		0.30
ClinPred		0.95	D
GERP RS		5.0
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.7
Varity_R		0.78
gMVP		0.81

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

LitVar

Other links and lift over

dbSNP: rs879253887; hg19: chr11-68702010;