rs149598003

Variant names:

Variant summary

Our verdict is Likely benign. The variant received -4 ACMG points: 0P and 4B. BP4_Strong

The NM_000057.4(BLM):c.847A>G(p.Thr283Ala) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.0000986 in 1,612,738 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 16/22 in silico tools predict a benign 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. T283N) has been classified as Uncertain significance.

Frequency

Genomes: 𝑓 0.000053 ( 0 hom., cov: 32)

Exomes 𝑓: 0.00010 ( 0 hom. )

Consequence

BLM
NM_000057.4 missense

Scores

Clinical Significance

Uncertain significance criteria provided, multiple submitters, no conflicts U:5O:1

Conservation

PhyloP100: -2.63

Publications

4 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:

Genome browser will be placed here

ACMG classification

Classification was made for transcript

Our verdict: Likely_benign. The variant received -4 ACMG points.

BP4

Computational evidence support a benign effect (MetaRNN=0.04011315).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
BLM	NM_000057.4 link	c.847A>G	p.Thr283Ala	missense_variant	Exon 4 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.847A>G	p.Thr283Ala	missense_variant	Exon 4 of 22	1	NM_000057.4	ENSP00000347232.3		P54132

Frequencies

GnomAD3 genomes

AF:

0.0000525

AC:

AN:

152274

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.00

Gnomad AMI

AF:

0.00

Gnomad AMR

AF:

0.0000654

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:

0.000103

Gnomad OTH

AF:

0.00

GnomAD2 exomes

AF:

0.0000318

AC:

AN:

251236

AF XY:

0.0000368

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:

0.0000616

Gnomad OTH exome

AF:

0.000163

GnomAD4 exome

AF:

0.000103

AC:

151

AN:

1460464

Hom.:

Cov.:

AF XY:

0.0000895

AC XY:

AN XY:

726630

show subpopulations

African (AFR)

AF:

0.00

AC:

AN:

33442

American (AMR)

AF:

0.00

AC:

AN:

44722

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

26118

East Asian (EAS)

AF:

0.00

AC:

AN:

39630

South Asian (SAS)

AF:

0.00

AC:

AN:

86220

European-Finnish (FIN)

AF:

0.0000187

AC:

AN:

53352

Middle Eastern (MID)

AF:

0.00

AC:

AN:

5764

European-Non Finnish (NFE)

AF:

0.000122

AC:

135

AN:

1110858

Other (OTH)

AF:

0.000249

AC:

AN:

60358

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.463

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:

0.0000525

AC:

AN:

152274

Hom.:

Cov.:

AF XY:

0.0000538

AC XY:

AN XY:

74402

show subpopulations

African (AFR)

AF:

0.00

AC:

AN:

41484

American (AMR)

AF:

0.0000654

AC:

AN:

15286

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

3472

East Asian (EAS)

AF:

0.00

AC:

AN:

5208

South Asian (SAS)

AF:

0.00

AC:

AN:

4830

European-Finnish (FIN)

AF:

0.00

AC:

AN:

10626

Middle Eastern (MID)

AF:

0.00

AC:

AN:

316

European-Non Finnish (NFE)

AF:

0.000103

AC:

AN:

68046

Other (OTH)

AF:

0.00

AC:

AN:

2094

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.513

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:

0.0000966

Hom.:

Bravo

AF:

0.0000642

ESP6500AA

AF:

0.00

AC:

ESP6500EA

AF:

0.000116

AC:

ExAC

AF:

0.0000494

AC:

EpiCase

AF:

0.000109

EpiControl

AF:

0.00

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:5Other:1

Revision: criteria provided, multiple submitters, no conflicts

LINK: link

Submissions by phenotype

Bloom syndrome

Uncertain:3

Apr 27, 2017

Illumina Laboratory Services, Illumina

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

This variant was observed as part of a predisposition screen in an ostensibly healthy population. A literature search was performed for the gene, cDNA change, and amino acid change (where applicable). No publications were found based on this search. Allele frequency data from public databases did not allow this variant to be ruled in or out of causing disease. Therefore, this variant is classified as a variant of unknown significance. -

May 24, 2018

Natera, Inc.

Significance:Uncertain significance

Review Status:no assertion criteria provided

Collection Method:clinical testing

- -

Jan 21, 2025

Labcorp Genetics (formerly Invitae), Labcorp

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

This sequence change replaces threonine, which is neutral and polar, with alanine, which is neutral and non-polar, at codon 283 of the BLM protein (p.Thr283Ala). This variant is present in population databases (rs149598003, gnomAD 0.006%). 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: 133711). 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 not expected to disrupt BLM protein function with a negative 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. -

not provided

Uncertain:1

Feb 13, 2024

Quest Diagnostics Nichols Institute San Juan Capistrano

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

The BLM c.847A>G (p.Thr283Ala) variant has been reported in the published literature in reportedly healthy individuals (PMID: 24728327 (2014)). The frequency of this variant in the general population, 0.000054 (7/129028 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 benign. Based on the available information, we are unable to determine the clinical significance of this variant. -

Hereditary cancer-predisposing syndrome

Uncertain:1

Feb 28, 2025

Ambry Genetics

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

The c.847A>G (p.T283A) alteration is located in exon 4 (coding exon 3) of the BLM gene. This alteration results from a A to G substitution at nucleotide position 847, causing the threonine (T) at amino acid position 283 to be replaced by an alanine (A). Based on insufficient or conflicting evidence, the clinical significance of this alteration remains unclear. -

not specified

Other:1

Sep 19, 2013

ITMI

Significance:not provided

Review Status:no classification provided

Collection Method:reference population

- -

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Benign

0.064

BayesDel_addAF

Benign

-0.48

BayesDel_noAF

Benign

-0.75

CADD

Benign

0.0010

(source)

DANN

Benign

0.73

DEOGEN2

Benign

0.051

T;.

Eigen

Benign

-1.7

Eigen_PC

Benign

-1.7

FATHMM_MKL

Benign

0.00078

LIST_S2

Benign

0.39

T;T

M_CAP

Benign

0.0059

MetaRNN

Benign

0.040

T;T

MetaSVM

Benign

-1.1

MutationAssessor

Benign

0.69

N;.

PhyloP100

-2.6

PrimateAI

Benign

0.25

PROVEAN

Benign

-0.64

N;N

REVEL

Benign

0.059

Sift

Benign

0.92

T;T

Sift4G

Benign

0.94

T;T

Polyphen

0.0

B;.

Vest4

0.056

MVP

0.55

MPC

0.087

ClinPred

0.033

GERP RS

-12

RBP_binding_hub_radar

0.0

RBP_regulation_power_radar

1.1

Varity_R

0.017

gMVP

0.068

Mutation Taster

=98/2

polymorphism

(source)

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

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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