15-90749459-A-T

Variant names:

Variant summary

Our verdict is Likely benign. The variant received -2 ACMG points: 0P and 2B. BP4BP6

The NM_000057.4(BLM):c.191A>T(p.Asp64Val) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000416 in 1,612,010 control chromosomes in the GnomAD database, including 1 homozygotes. In-silico tool predicts a benign 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. D64Y) has been classified as Uncertain significance.

Frequency

Genomes: 𝑓 0.00026 ( 0 hom., cov: 32)

Exomes 𝑓: 0.00043 ( 1 hom. )

Consequence

BLM
NM_000057.4 missense

Scores

Clinical Significance

Conflicting classifications of pathogenicity criteria provided, conflicting classifications U:9B:4

Conservation

PhyloP100: 2.43

Publications

11 publications found

Variant links:

COSMIC-nc: COSV104665713

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:

Genome browser will be placed here

ACMG classification

Classification was made for transcript

Our verdict: Likely_benign. The variant received -2 ACMG points.

BP4

Computational evidence support a benign effect (MetaRNN=0.36249626).

BP6

Variant 15-90749459-A-T is Benign according to our data. Variant chr15-90749459-A-T is described in ClinVar as Conflicting_classifications_of_pathogenicity. ClinVar VariationId is 127479.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
BLM	NM_000057.4 link	c.191A>T	p.Asp64Val	missense_variant	Exon 3 of 22	ENST00000355112.8	NP_000048.1	P54132

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
BLM	ENST00000355112.8 link	c.191A>T	p.Asp64Val	missense_variant	Exon 3 of 22	1	NM_000057.4	ENSP00000347232.3		P54132

Frequencies

GnomAD3 genomes

AF:

0.000263

AC:

AN:

152254

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.0000482

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:

0.000558

Gnomad OTH

AF:

0.00

GnomAD2 exomes

AF:

0.000239

AC:

AN:

250804

AF XY:

0.000243

show subpopulations

Gnomad AFR exome

AF:

0.000125

Gnomad AMR exome

AF:

0.0000289

Gnomad ASJ exome

AF:

0.00

Gnomad EAS exome

AF:

0.00

Gnomad FIN exome

AF:

0.00

Gnomad NFE exome

AF:

0.000503

Gnomad OTH exome

AF:

0.00

GnomAD4 exome

AF:

0.000432

AC:

631

AN:

1459756

Hom.:

Cov.:

AF XY:

0.000403

AC XY:

293

AN XY:

726364

show subpopulations

African (AFR)

AF:

0.0000598

AC:

AN:

33434

American (AMR)

AF:

0.0000224

AC:

AN:

44718

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

26118

East Asian (EAS)

AF:

0.00

AC:

AN:

39680

South Asian (SAS)

AF:

0.0000116

AC:

AN:

86216

European-Finnish (FIN)

AF:

0.0000187

AC:

AN:

53412

Middle Eastern (MID)

AF:

0.000173

AC:

AN:

5766

European-Non Finnish (NFE)

AF:

0.000545

AC:

605

AN:

1110094

Other (OTH)

AF:

0.000332

AC:

AN:

60318

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.490

Heterozygous variant carriers

108

144

180

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Age Distribution

Exome Het

Variant carriers

100

<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:

0.000263

AC:

AN:

152254

Hom.:

Cov.:

AF XY:

0.000242

AC XY:

AN XY:

74380

show subpopulations

African (AFR)

AF:

0.0000482

AC:

AN:

41468

American (AMR)

AF:

0.00

AC:

AN:

15292

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

3472

East Asian (EAS)

AF:

0.00

AC:

AN:

5196

South Asian (SAS)

AF:

0.00

AC:

AN:

4832

European-Finnish (FIN)

AF:

0.00

AC:

AN:

10624

Middle Eastern (MID)

AF:

0.00

AC:

AN:

316

European-Non Finnish (NFE)

AF:

0.000558

AC:

AN:

68050

Other (OTH)

AF:

0.00

AC:

AN:

2092

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.523

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:

0.000410

Hom.:

Bravo

AF:

0.000261

TwinsUK

AF:

0.00108

AC:

ALSPAC

AF:

0.000519

AC:

ESP6500AA

AF:

0.00

AC:

ESP6500EA

AF:

0.000349

AC:

ExAC

AF:

0.000313

AC:

EpiCase

AF:

0.000436

EpiControl

AF:

0.000415

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Uncertain:9Benign:4

Revision: criteria provided, conflicting classifications

LINK: link

Submissions by phenotype

Bloom syndrome

Uncertain:3Benign:2

May 18, 2021

Genome-Nilou Lab

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

- -

Jun 17, 2025

St. Jude Molecular Pathology, St. Jude Children's Research Hospital

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

The BLM c.191A>T p.(Asp64Val) missense change has a maximum subpopulation frequency of 0.054% in gnomAD v2.1.1, including one homozygote (https://gnomad.broadinstitute.org/). The in silico tool REVEL is inconclusive about a pathogenic or benign effect of this variant on protein function, and to our knowledge functional studies have not been performed. This variant has been identified in 2 of 1358 non-cancer control individuals in a study of individuals with multiple primary cancers (PMID: 29641532). To our knowledge, this variant has not been reported in individuals with Bloom syndrome. In summary, the evidence currently available is insufficient to determine the clinical significance of this variant. It has therefore been classified as of uncertain significance. -

May 23, 2017

Fulgent Genetics, Fulgent Genetics

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

- -

Aug 06, 2019

Natera, Inc.

Significance:Benign

Review Status:no assertion criteria provided

Collection Method:clinical testing

- -

Feb 02, 2025

Labcorp Genetics (formerly Invitae), Labcorp

Significance:Benign

Review Status:criteria provided, single submitter

Collection Method:clinical testing

- -

not provided

Uncertain:3Benign:1

Nov 03, 2021

Institute for Clinical Genetics, University Hospital TU Dresden, University Hospital TU Dresden

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

- -

May 02, 2025

GeneDx

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

In silico analysis supports that this missense variant has a deleterious effect on protein structure/function; Identified in individuals with a personal history of breast, colorectal, or other cancers (PMID: 31159747, 30613976, 33606809, 28944238, 26580448); This variant is associated with the following publications: (PMID: 26580448, 30613976, 28944238, 31937788, 33606809, 31159747) -

Jul 11, 2023

Quest Diagnostics Nichols Institute San Juan Capistrano

Significance:Likely benign

Review Status:criteria provided, single submitter

Collection Method:clinical testing

- -

Apr 24, 2015

Eurofins Ntd Llc (ga)

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

- -

Hereditary cancer-predisposing syndrome

Uncertain:2Benign:1

Jun 13, 2018

Ambry Genetics

Significance:Likely benign

Review Status:criteria provided, single submitter

Collection Method:clinical testing

This alteration is classified as likely benign based on a combination of the following: seen in unaffected individuals, population frequency, intact protein function, lack of segregation with disease, co-occurrence, RNA analysis, in silico models, amino acid conservation, lack of disease association in case-control studies, and/or the mechanism of disease or impacted region is inconsistent with a known cause of pathogenicity. -

Mar 03, 2022

Sema4, Sema4

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:curation

- -

Aug 01, 2018

GeneKor MSA

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

- -

not specified

Uncertain:1

May 11, 2022

Women's Health and Genetics/Laboratory Corporation of America, LabCorp

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

Variant summary: BLM c.191A>T (p.Asp64Val) results in a non-conservative amino acid change located in the Bloom syndrome protein, N-terminal domain (IPR032437) of the encoded protein sequence. Four of five in-silico tools predict a damaging effect of the variant on protein function. The variant allele was found at a frequency of 0.00024 in 250804 control chromosomes, predominantly at a frequency of 0.0005 within the Non-Finnish European subpopulation in the gnomAD database, including 1 homozygote. This frequency is not significantly higher than expected for a pathogenic variant in BLM causing Bloom Syndrome (0.00024 vs 0.0035), allowing no conclusion about variant significance. c.191A>T has been reported in the literature in individuals affected with autosomal dominant cancer-predisposition syndromes, breast and/or ovarian cancer (Zhang_2015, Rizzolo_2019, Tsaousis_2019, Sandoval_2021). These reports do not provide unequivocal conclusions about association of the variant with Bloom Syndrome. To our knowledge, no experimental evidence demonstrating an impact on protein function has been reported. Eleven ClinVar submitters (evaluation after 2014) cite the variant as uncertain significance (n=7), likely benign (n=3) and benign (n=1). Based on the evidence outlined above, the variant was classified as uncertain significance. -

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Benign

0.18

BayesDel_addAF

Benign

-0.13

BayesDel_noAF

Uncertain

-0.030

CADD

Benign

(source)

DANN

Uncertain

0.99

DEOGEN2

Benign

0.25

T;.

Eigen

Uncertain

0.34

Eigen_PC

Uncertain

0.28

FATHMM_MKL

Uncertain

0.83

LIST_S2

Benign

0.84

T;T

M_CAP

Uncertain

0.11

MetaRNN

Benign

0.36

T;T

MetaSVM

Benign

-0.67

MutationAssessor

Uncertain

2.4

M;.

PhyloP100

2.4

PrimateAI

Benign

0.38

PROVEAN

Uncertain

-2.8

D;D

REVEL

Uncertain

0.31

Sift

Uncertain

0.0010

D;D

Sift4G

Uncertain

0.0060

D;D

Polyphen

0.99

D;.

Vest4

0.54

MVP

0.84

MPC

0.52

ClinPred

0.25

GERP RS

3.5

Varity_R

0.34

gMVP

0.28

Mutation Taster

=95/5

polymorphism

(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

Transcripts

RefSeq

Ensembl

Frequencies

Age Distribution

Age Distribution

ClinVar

Submissions by phenotype

Computational scores

Splicing

Publications

Other links and lift over