rs764587569

Variant names:

Variant summary

Our verdict is Uncertain significance. The variant received 4 ACMG points: 4P and 0B. PM1PP3_Moderate

The NM_000057.4(BLM):c.2674A>G(p.Ile892Val) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.0000062 in 1,613,582 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 (★★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. I892M) has been classified as Uncertain significance.

Frequency

Genomes: 𝑓 0.000013 ( 0 hom., cov: 31)

Exomes 𝑓: 0.0000055 ( 0 hom. )

Consequence

BLM
NM_000057.4 missense

Scores

Clinical Significance

Uncertain significance criteria provided, multiple submitters, no conflicts U:5

Conservation

PhyloP100: 9.21

Publications

1 publications found

Variant links:

Genes affected

BLM (HGNC:1058): (BLM RecQ like helicase) The Bloom syndrome is an autosomal recessive disorder characterized by growth deficiency, microcephaly and immunodeficiency among others. It is caused by homozygous or compound heterozygous mutation in the gene encoding DNA helicase RecQ protein on chromosome 15q26. This Bloom-associated helicase unwinds a variety of DNA substrates including Holliday junction, and is involved in several pathways contributing to the maintenance of genome stability. Identification of pathogenic Bloom variants is required for heterozygote testing in at-risk families. [provided by RefSeq, May 2020]

BLM Gene-Disease associations (from GenCC):

Bloom syndrome
Inheritance: AR Classification: DEFINITIVE, STRONG, MODERATE, SUPPORTIVE Submitted by: Myriad Women’s Health, Labcorp Genetics (formerly Invitae), G2P, Laboratory for Molecular Medicine, Orphanet, Genomics England PanelApp, ClinGen
osteosarcoma
Inheritance: AR Classification: MODERATE Submitted by: Genomics England PanelApp
breast cancer
Inheritance: AD Classification: NO_KNOWN Submitted by: Ambry Genetics
hereditary nonpolyposis colon cancer
Inheritance: AD Classification: NO_KNOWN Submitted by: Ambry Genetics

BLM links:

ENSG00000300894 (HGNC:):

ENSG00000300894 links:

Genome browser will be placed here

ACMG classification

Classification was made for transcript

Our verdict: Uncertain_significance. The variant received 4 ACMG points.

PM1

In a hotspot region, there are 2 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 1 benign, 23 uncertain in NM_000057.4

PP3

MetaRNN computational evidence supports a deleterious effect, 0.873

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_000057.4. You can select a different transcript below to see updated ACMG assignments.

RefSeq Transcripts

Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein
BLM	NM_000057.4	MANE Select	c.2674A>G	p.Ile892Val	missense	Exon 14 of 22	NP_000048.1
BLM	NM_001287246.2		c.2674A>G	p.Ile892Val	missense	Exon 15 of 23	NP_001274175.1
BLM	NM_001287247.2		c.2674A>G	p.Ile892Val	missense	Exon 14 of 20	NP_001274176.1

Ensembl Transcripts

Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein
BLM	ENST00000355112.8	TSL:1 MANE Select	c.2674A>G	p.Ile892Val	missense	Exon 14 of 22	ENSP00000347232.3
BLM	ENST00000560509.5	TSL:1	c.2674A>G	p.Ile892Val	missense	Exon 14 of 20	ENSP00000454158.1
BLM	ENST00000559724.5	TSL:1	n.*1598A>G		non_coding_transcript_exon	Exon 14 of 22	ENSP00000453359.1

Frequencies

GnomAD3 genomes

AF:

0.0000131

AC:

AN:

152130

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.0000483

Gnomad AMI

AF:

0.00

Gnomad AMR

AF:

0.00

Gnomad ASJ

AF:

0.00

Gnomad EAS

AF:

0.00

Gnomad SAS

AF:

0.00

Gnomad FIN

AF:

0.00

Gnomad MID

AF:

0.00

Gnomad NFE

AF:

0.00

Gnomad OTH

AF:

0.00

GnomAD2 exomes

AF:

0.00000398

AC:

AN:

251326

AF XY:

0.00

show subpopulations

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 FIN exome

AF:

0.00

Gnomad NFE exome

AF:

0.00000880

Gnomad OTH exome

AF:

0.00

GnomAD4 exome

AF:

0.00000547

AC:

AN:

1461452

Hom.:

Cov.:

AF XY:

0.00000275

AC XY:

AN XY:

726954

show subpopulations

African (AFR)

AF:

0.00

AC:

AN:

33480

American (AMR)

AF:

0.00

AC:

AN:

44706

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

26136

East Asian (EAS)

AF:

0.00

AC:

AN:

39688

South Asian (SAS)

AF:

0.00

AC:

AN:

86234

European-Finnish (FIN)

AF:

0.00

AC:

AN:

53390

Middle Eastern (MID)

AF:

0.00

AC:

AN:

5768

European-Non Finnish (NFE)

AF:

0.00000720

AC:

AN:

1111670

Other (OTH)

AF:

0.00

AC:

AN:

60380

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.444

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Age Distribution

Exome Het

Variant carriers

<30

30-35

35-40

40-45

45-50

50-55

55-60

60-65

65-70

70-75

75-80

>80

Age

GnomAD4 genome

AF:

0.0000131

AC:

AN:

152130

Hom.:

Cov.:

AF XY:

0.0000135

AC XY:

AN XY:

74324

show subpopulations

African (AFR)

AF:

0.0000483

AC:

AN:

41424

American (AMR)

AF:

0.00

AC:

AN:

15262

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

3468

East Asian (EAS)

AF:

0.00

AC:

AN:

5202

South Asian (SAS)

AF:

0.00

AC:

AN:

4826

European-Finnish (FIN)

AF:

0.00

AC:

AN:

10614

Middle Eastern (MID)

AF:

0.00

AC:

AN:

316

European-Non Finnish (NFE)

AF:

0.00

AC:

AN:

68018

Other (OTH)

AF:

0.00

AC:

AN:

2090

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.500

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Age Distribution

Genome Het

Variant carriers

<30

30-35

35-40

40-45

45-50

50-55

55-60

60-65

65-70

70-75

75-80

>80

Age

Alfa

AF:

0.00

Hom.:

Bravo

AF:

0.0000227

ExAC

AF:

0.00000824

AC:

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:5

Revision: criteria provided, multiple submitters, no conflicts

LINK: link

Submissions by phenotype

Bloom syndrome

Uncertain:3

Nov 29, 2018

Natera, Inc.

Significance:Uncertain significance

Review Status:no assertion criteria provided

Collection Method:clinical testing

Sep 25, 2024

Labcorp Genetics (formerly Invitae), Labcorp

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

This sequence change replaces isoleucine, which is neutral and non-polar, with valine, which is neutral and non-polar, at codon 892 of the BLM protein (p.Ile892Val). This variant is present in population databases (rs764587569, gnomAD 0.0009%). This variant has not been reported in the literature in individuals affected with BLM-related conditions. ClinVar contains an entry for this variant (Variation ID: 485341). Invitae Evidence Modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) indicates that this missense variant is expected to disrupt BLM protein function with a positive predictive value of 80%. RNA analysis performed to evaluate the impact of this missense change on mRNA splicing indicates it does not significantly alter splicing (internal data). 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.

Aug 04, 2021

Fulgent Genetics, Fulgent Genetics

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

not provided

Uncertain:1

Aug 12, 2024

Quest Diagnostics Nichols Institute San Juan Capistrano

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

The BLM c.2674A>G (p.Ile892Val) variant has not been reported in individuals with BLM-related conditions in the published literature. The frequency of this variant in the general population, 0.000004 (1/251326 chromosomes (Genome Aggregation Database, http://gnomad.broadinstitute.org)), is uninformative in the assessment of its pathogenicity. Analysis of this variant using bioinformatics tools for the prediction of the effect of amino acid changes on protein structure and function yielded predictions that this variant is damaging. Additional analysis using software algorithms for the prediction of the effect of nucleotide changes on BLM mRNA splicing yielded predictions that this variant may result in the gain of a cryptic splice site without affecting the natural splice sites. Based on the available information, we are unable to determine the clinical significance of this variant.

Hereditary cancer-predisposing syndrome

Uncertain:1

Jul 28, 2024

Ambry Genetics

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

The p.I892V variant (also known as c.2674A>G), located in coding exon 13 of the BLM gene, results from an A to G substitution at nucleotide position 2674. The isoleucine at codon 892 is replaced by valine, an amino acid with highly similar properties. This amino acid position is highly conserved in available vertebrate species. In addition, the in silico prediction for this alteration is inconclusive. Since supporting evidence is limited at this time, the clinical significance of this alteration remains unclear.

Computational scores

Source: dbNSFP v4.9

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Uncertain

0.39

BayesDel_addAF

Pathogenic

0.22

BayesDel_noAF

Uncertain

0.080

CADD

Pathogenic

(source)

DANN

Pathogenic

1.0

DEOGEN2

Benign

0.38

Eigen

Pathogenic

0.87

Eigen_PC

Pathogenic

0.86

FATHMM_MKL

Pathogenic

0.99

LIST_S2

Uncertain

0.92

M_CAP

Uncertain

0.10

MetaRNN

Pathogenic

0.87

MetaSVM

Uncertain

0.20

MutationAssessor

Uncertain

2.6

PhyloP100

9.2

PrimateAI

Uncertain

0.65

PROVEAN

Benign

-0.98

REVEL

Uncertain

0.60

Sift

Pathogenic

0.0

Sift4G

Pathogenic

0.0

Polyphen

1.0

Vest4

0.75

MutPred

0.74

Gain of catalytic residue at I892 (P = 0.0405)

MVP

0.94

MPC

0.44

ClinPred

0.94

GERP RS

5.8

Varity_R

0.64

gMVP

0.58

Mutation Taster

=45/55

disease causing

(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

Publications

ACMG classification

Variant Effect in Transcripts

RefSeq Transcripts

Ensembl Transcripts

Frequencies

Age Distribution

Age Distribution

ClinVar

Submissions by phenotype

Computational scores

Splicing

Publications

Other links and lift over