15-90769505-C-T

Variant names:

Variant summary

Our verdict is Uncertain significance. Variant got 4 ACMG points: 4P and 0B. PM2PP3_Moderate

The NM_000057.4(BLM):c.2474C>T(p.Pro825Leu) variant causes a missense change. The variant allele was found at a frequency of 0.0000242 in 1,613,792 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: 𝑓 0.000020 ( 0 hom., cov: 32)

Exomes 𝑓: 0.000025 ( 0 hom. )

Consequence

BLM
NM_000057.4 missense

Scores

Clinical Significance

Uncertain significance criteria provided, multiple submitters, no conflicts U:9

Conservation

PhyloP100: 4.78

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 links:

Genome browser will be placed here

ACMG classification

Classification made for transcript

Verdict is Uncertain_significance. Variant got 4 ACMG points.

PM2

Very rare variant in population databases, with high coverage;

PP3

MetaRNN computational evidence supports a deleterious effect, 0.861

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
BLM	NM_000057.4 link	c.2474C>T	p.Pro825Leu	missense_variant	Exon 12 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.2474C>T	p.Pro825Leu	missense_variant	Exon 12 of 22	1	NM_000057.4	ENSP00000347232.3		P54132

Frequencies

GnomAD3 genomes

AF:

0.0000197

AC:

AN:

152078

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.00

Gnomad AMI

AF:

0.00

Gnomad AMR

AF:

0.00

Gnomad ASJ

AF:

0.00

Gnomad EAS

AF:

0.000193

Gnomad SAS

AF:

0.00

Gnomad FIN

AF:

0.00

Gnomad MID

AF:

0.00

Gnomad NFE

AF:

0.0000294

Gnomad OTH

AF:

0.00

GnomAD3 exomes

AF:

0.0000239

AC:

AN:

251430

Hom.:

AF XY:

0.0000294

AC XY:

AN XY:

135896

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 SAS exome

AF:

0.0000327

Gnomad FIN exome

AF:

0.00

Gnomad NFE exome

AF:

0.0000440

Gnomad OTH exome

AF:

0.00

GnomAD4 exome

AF:

0.0000246

AC:

AN:

1461714

Hom.:

Cov.:

AF XY:

0.0000275

AC XY:

AN XY:

727156

show subpopulations

Gnomad4 AFR exome

AF:

0.00

Gnomad4 AMR exome

AF:

0.0000224

Gnomad4 ASJ exome

AF:

0.00

Gnomad4 EAS exome

AF:

0.000101

Gnomad4 SAS exome

AF:

0.0000116

Gnomad4 FIN exome

AF:

0.00

Gnomad4 NFE exome

AF:

0.0000234

Gnomad4 OTH exome

AF:

0.0000497

GnomAD4 genome

AF:

0.0000197

AC:

AN:

152078

Hom.:

Cov.:

AF XY:

0.0000135

AC XY:

AN XY:

74272

show subpopulations

Gnomad4 AFR

AF:

0.00

Gnomad4 AMR

AF:

0.00

Gnomad4 ASJ

AF:

0.00

Gnomad4 EAS

AF:

0.000193

Gnomad4 SAS

AF:

0.00

Gnomad4 FIN

AF:

0.00

Gnomad4 NFE

AF:

0.0000294

Gnomad4 OTH

AF:

0.00

Alfa

AF:

0.0000564

Hom.:

Bravo

AF:

0.0000227

ExAC

AF:

0.0000412

AC:

EpiCase

AF:

0.000109

EpiControl

AF:

0.000119

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:9

Revision: criteria provided, multiple submitters, no conflicts

LINK: link

Submissions by phenotype

Bloom syndrome

Uncertain:4

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 proline, which is neutral and non-polar, with leucine, which is neutral and non-polar, at codon 825 of the BLM protein (p.Pro825Leu). This variant is present in population databases (rs749632465, gnomAD 0.004%). 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: 405283). 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%. 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. -

Nov 16, 2017

Natera, Inc.

Significance: Uncertain significance

Review Status: no assertion criteria provided

Collection Method: clinical testing

- -

Jul 14, 2021

Genome-Nilou Lab

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Jul 02, 2018

Mendelics

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

not specified

Uncertain:2

Dec 05, 2019

Genetic Services Laboratory, University of Chicago

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Jan 13, 2025

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.2474C>T (p.Pro825Leu) results in a non-conservative amino acid change located in the Helicase superfamily 1/2, ATP-binding domain (IPR014001) 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 2.4e-05 in 251430 control chromosomes (gnomAD). The available data on variant occurrences in the general population are insufficient to allow any conclusion about variant significance. c.2474C>T has been reported in the literature in individuals affected with diffuse-type gastric cancer or breast cancer (Tedaldi_2019, Guindalini_2022). 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. The following publications have been ascertained in the context of this evaluation (PMID: 35264596, 36230663, 31514334). ClinVar contains an entry for this variant (Variation ID: 405283). Based on the evidence outlined above, the variant was classified as uncertain significance. -

not provided

Uncertain:2

Dec 28, 2023

Quest Diagnostics Nichols Institute San Juan Capistrano

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The BLM c.2474C>T (p.Pro825Leu) variant has been reported in the published literature in individuals with breast cancer (PMID: 35264596 (2022)), colorectal cancer (PMID: 28944238 (2017)), and diffuse gastric cancer (PMID: 31514334 (2019)). The frequency of this variant in the general population, 0.000044 (5/113726 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. Based on the available information, we are unable to determine the clinical significance of this variant. -

Nov 10, 2022

GeneDx

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Not observed at significant frequency in large population cohorts (gnomAD); In silico analysis supports that this missense variant has a deleterious effect on protein structure/function; Observed in individuals with primary ovarian insufficiency (Gorsi et al., 2021); This variant is associated with the following publications: (PMID: 32704157, 34718612) -

Hereditary cancer-predisposing syndrome

Uncertain:1

Jun 03, 2024

Ambry Genetics

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The p.P825L variant (also known as c.2474C>T), located in coding exon 11 of the BLM gene, results from a C to T substitution at nucleotide position 2474. The proline at codon 825 is replaced by leucine, an amino acid with similar properties. In one study, this alteration was detected in 1/1231 colorectal cancer patients and 0/93 controls (DeRycke MS et al. Mol Genet Genomic Med, 2017 Sep;5:553-569). This amino acid position is well 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 v4.3

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Pathogenic

0.64

BayesDel_addAF

Benign

-0.017

BayesDel_noAF

Benign

-0.13

CADD

Pathogenic

DANN

Uncertain

1.0

DEOGEN2

Benign

0.39

T;.

Eigen

Pathogenic

0.82

Eigen_PC

Pathogenic

0.74

FATHMM_MKL

Pathogenic

0.99

LIST_S2

Pathogenic

0.98

D;D

M_CAP

Benign

0.064

MetaRNN

Pathogenic

0.86

D;D

MetaSVM

Benign

-0.63

MutationAssessor

Pathogenic

3.2

M;.

PrimateAI

Uncertain

0.73

PROVEAN

Pathogenic

-8.4

D;D

REVEL

Uncertain

0.33

Sift

Uncertain

0.0020

D;D

Sift4G

Uncertain

0.0060

D;D

Polyphen

1.0

D;.

Vest4

0.85

MVP

0.83

MPC

0.48

ClinPred

0.98

GERP RS

5.2

RBP_binding_hub_radar

0.0

RBP_regulation_power_radar

1.1

Varity_R

0.93

gMVP

0.84

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

Below is the list of publications found by LitVar. It may be empty.

Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

ACMG classification

Transcripts

RefSeq

Ensembl

Frequencies

ClinVar

Submissions by phenotype

Computational scores

Splicing

Publications

LitVar

Other links and lift over