chr7-76302732-C-G

Position:

• chr7-76302732-C-G

Variant summary

Our verdict is Likely pathogenic. Variant got 9 ACMG points: 9P and 0B. PM1 PM2 PM5 PP3_Moderate PP5

The NM_001540.5(HSPB1):​c.20C>G​(p.Pro7Arg) variant causes a missense change. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. P7S) has been classified as Likely pathogenic.

• Frequency: Genomes: not found (cov: 33)
• Consequence: HSPB1 NM_001540.5 missense
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications P:1 U:1
• Conservation: PhyloP100: 7.18

Genes affected

HSPB1 (HGNC:5246): (heat shock protein family B (small) member 1) This gene encodes a member of the small heat shock protein (HSP20) family of proteins. In response to environmental stress, the encoded protein translocates from the cytoplasm to the nucleus and functions as a molecular chaperone that promotes the correct folding of other proteins. This protein plays an important role in the differentiation of a wide variety of cell types. Expression of this gene is correlated with poor clinical outcome in multiple human cancers, and the encoded protein may promote cancer cell proliferation and metastasis, while protecting cancer cells from apoptosis. Mutations in this gene have been identified in human patients with Charcot-Marie-Tooth disease and distal hereditary motor neuropathy. [provided by RefSeq, Aug 2017]

ACMG classification

Verdict is Likely_pathogenic. Variant got 9 ACMG points.

• PM1: In a chain Heat shock protein beta-1 (size 204) in uniprot entity HSPB1_HUMAN there are 63 pathogenic changes around while only 11 benign (85%) in NM_001540.5
• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chr7-76302731-C-T is described in ClinVar as [Conflicting_classifications_of_pathogenicity]. Clinvar id is 560407.We mark this variant Likely_pathogenic, oryginal submissions are: {Likely_pathogenic=1, Uncertain_significance=1}.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.914
• PP5: Variant 7-76302732-C-G is Pathogenic according to our data. Variant chr7-76302732-C-G is described in ClinVar as [Conflicting_classifications_of_pathogenicity]. Clinvar id is 581452.We mark this variant Likely_pathogenic, oryginal submissions are: {Likely_pathogenic=1, Uncertain_significance=1}.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
HSPB1	NM_001540.5	c.20C>G	p.Pro7Arg	missense_variant	1/3	ENST00000248553.7

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
HSPB1	ENST00000248553.7	c.20C>G	p.Pro7Arg	missense_variant	1/3	1	NM_001540.5	P1

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome Cov.: 31

GnomAD4 genome Cov.: 33

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Pathogenic:1 Uncertain:1

Revision: criteria provided, conflicting classifications

Submissions by phenotype

Charcot-Marie-Tooth disease axonal type 2F Pathogenic:1

Likely pathogenic, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Oct 24, 2020

In summary, the currently available evidence indicates that the variant is pathogenic, but additional data are needed to prove that conclusively. Therefore, this variant has been classified as Likely Pathogenic. This variant disrupts the p.Pro7 amino acid residue in HSPB1. Other variant(s) that disrupt this residue have been observed in individuals with HSPB1-related conditions (PMID: 28144995), which suggests that this may be a clinically significant amino acid residue. Algorithms developed to predict the effect of missense changes on protein structure and function (SIFT, PolyPhen-2, Align-GVGD) all suggest that this variant is likely to be disruptive, but these predictions have not been confirmed by published functional studies and their clinical significance is uncertain. This variant has been observed in individual(s) with HSPB1-related conditions (PMID: 26989944, 29031079). It has also been observed to segregate with disease in related individuals. ClinVar contains an entry for this variant (Variation ID: 581452). This variant is not present in population databases (ExAC no frequency). This sequence change replaces proline with arginine at codon 7 of the HSPB1 protein (p.Pro7Arg). The proline residue is highly conserved and there is a moderate physicochemical difference between proline and arginine. -

not provided Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

GeneDx

Dec 05, 2023

Reported previously as a likely pathogenic variant in a patient with a diagnosis of distal hereditary motor neuropathy; however, no further clinical or segregation information was provided (PMID: 26989944); In silico analysis supports that this missense variant has a deleterious effect on protein structure/function; Not observed at significant frequency in large population cohorts (gnomAD); This variant is associated with the following publications: (PMID: 29031079, 26989944, 28018906, 32323160, 28144995, 32301006, 32334137, 32639100) -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Uncertain	0.56
BayesDel_addAF	Pathogenic	0.46	D
BayesDel_noAF	Pathogenic	0.43
CADD	Pathogenic	29
DANN	Uncertain	1.0
DEOGEN2	Uncertain	0.74	D
Eigen	Pathogenic	0.83
Eigen_PC	Pathogenic	0.77
FATHMM_MKL	Pathogenic	0.98	D
LIST_S2	Uncertain	0.88	D
M_CAP	Pathogenic	0.71	D
MetaRNN	Pathogenic	0.91	D
MetaSVM	Pathogenic	0.89	D
MutationAssessor	Pathogenic	2.9	M
MutationTaster	Benign	1.0	D
PrimateAI	Pathogenic	0.88	D
PROVEAN	Uncertain	-3.2	D
REVEL	Pathogenic	0.88
Sift	Uncertain	0.0050	D
Sift4G	Uncertain	0.016	D
Polyphen		1.0	D
Vest4		0.87
MutPred		0.56		Gain of MoRF binding (P = 1e-04);
MVP		0.99
MPC		1.5
ClinPred		0.99	D
GERP RS		4.9
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.7
Varity_R		0.87
gMVP		0.96

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: rs1405359814; hg19: chr7-75932049;