NM_006308.3:c.2T>C

Variant names:

• chr5-54455791-T-C
• rs769845878
• NM_006308.3:c.2T>C

Variant summary

Our verdict is Likely benign. Variant got -3 ACMG points: 1P and 4B. PVS1_Supporting BS2

The NM_006308.3(HSPB3):​c.2T>C​(p.Met1?) variant causes a start lost change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.0000137 in 1,461,648 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 Uncertain significance (★).

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.000014 (0 hom.)
• Consequence: HSPB3 NM_006308.3 start_lost
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 3.39

Genes affected

HSPB3 (HGNC:5248): (heat shock protein family B (small) member 3) This gene encodes a muscle-specific small heat shock protein. A mutation in this gene is the cause of autosomal dominant distal hereditary motor neuropathy type 2C.[provided by RefSeq, Sep 2010]

ACMG classification

Verdict is Likely_benign. Variant got -3 ACMG points.

• PVS1: Start lost variant, no pathogenic variants between lost start and next in-frame start position. Next in-frame start position is after 104 codons. Genomic position: 54456099. Lost 0.684 part of the original CDS.
• BS2: High AC in GnomAdExome4 at 20 AD gene.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
HSPB3	NM_006308.3	c.2T>C	p.Met1?	start_lost	Exon 1 of 1	ENST00000302005.3	NP_006299.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
HSPB3	ENST00000302005.3	c.2T>C	p.Met1?	start_lost	Exon 1 of 1	6	NM_006308.3	ENSP00000303394.1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD3 exomes AF: 0.0000796 AC: 20 AN: 251172 Hom.: 0 AF XY: 0.0000442 AC XY: 6 AN XY: 135746

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.000578

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: 0.00

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.0000137 AC: 20 AN: 1461648 Hom.: 0 Cov.: 31 AF XY: 0.00000688 AC XY: 5 AN XY: 727142

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.000447

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 32

Alfa AF: 0.0000680 Hom.: 0

Bravo AF: 0.0000378

ExAC AF: 0.0000988 AC: 12

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Neuronopathy, distal hereditary motor, type 2C Uncertain:1

Sep 21, 2024

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change affects the initiator methionine of the HSPB3 mRNA. The next in-frame methionine is located at codon 104. This variant is present in population databases (rs769845878, gnomAD 0.06%), and has an allele count higher than expected for a pathogenic variant. This variant has not been reported in the literature in individuals affected with HSPB3-related conditions. ClinVar contains an entry for this variant (Variation ID: 1019333). In summary, the available evidence is currently insufficient to determine the role of this variant in disease. Therefore, it has been classified as a Variant of Uncertain Significance. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Uncertain	0.11	D
BayesDel_noAF	Pathogenic	0.27
CADD	Uncertain	24
DANN	Uncertain	0.99
DEOGEN2	Benign	0.065	T
Eigen	Uncertain	0.32
Eigen_PC	Uncertain	0.34
FATHMM_MKL	Uncertain	0.84	D
LIST_S2	Uncertain	0.90	D
M_CAP	Pathogenic	0.51	D
MetaRNN	Pathogenic	0.76	D
MetaSVM	Uncertain	0.54	D
PROVEAN	Benign	-1.6	N
REVEL	Pathogenic	0.77
Sift	Pathogenic	0.0	D
Sift4G	Pathogenic	0.0	D
Polyphen		0.89	P
Vest4		0.82
MVP		0.95
ClinPred		0.79	D
GERP RS		4.8
Varity_R		0.85
gMVP		0.54

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: rs769845878; hg19: chr5-53751621; COSMIC: COSV57357150;