rs759330541

Positions:

chr15-90769453-C-T

Variant summary

Our verdict is Likely pathogenic. Variant got 8 ACMG points: 8P and 0B. PM1PM2PP3_Strong

The NM_000057.4(BLM):c.2422C>T(p.Arg808Cys) variant causes a missense change. The variant allele was found at a frequency of 0.000031 in 1,613,944 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 0.000013 ( 0 hom., cov: 32)

Exomes 𝑓: 0.000033 ( 0 hom. )

Consequence

BLM
NM_000057.4 missense

Scores

Clinical Significance

Uncertain significance criteria provided, multiple submitters, no conflicts U:6

Conservation

PhyloP100: 4.64

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:

BLM (HGNC:):

BLM links:

Genome browser will be placed here

ACMG classification

Classification made for transcript

Verdict is Likely_pathogenic. Variant got 8 ACMG points.

PM1

In a site 3' overhang DNA-binding (size 0) in uniprot entity BLM_HUMAN

PM2

Very rare variant in population databases, with high coverage;

PP3

MetaRNN computational evidence supports a deleterious effect, 0.971

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
BLM	NM_000057.4 linkuse as main transcript	c.2422C>T	p.Arg808Cys	missense_variant	12/22	ENST00000355112.8	NP_000048.1	P54132

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
BLM	ENST00000355112.8 linkuse as main transcript	c.2422C>T	p.Arg808Cys	missense_variant	12/22	1	NM_000057.4	ENSP00000347232.3		P54132

Frequencies

GnomAD3 genomes

AF:

0.0000132

AC:

AN:

152066

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:

0.00

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:

0.0000398

AC:

AN:

251434

Hom.:

AF XY:

0.0000368

AC XY:

AN XY:

135892

show subpopulations

Gnomad AFR exome

AF:

0.0000615

Gnomad AMR exome

AF:

0.00

Gnomad ASJ exome

AF:

0.00

Gnomad EAS exome

AF:

0.00

Gnomad SAS exome

AF:

0.00

Gnomad FIN exome

AF:

0.00

Gnomad NFE exome

AF:

0.0000703

Gnomad OTH exome

AF:

0.000163

GnomAD4 exome

AF:

0.0000328

AC:

AN:

1461878

Hom.:

Cov.:

AF XY:

0.0000330

AC XY:

AN XY:

727244

show subpopulations

Gnomad4 AFR exome

AF:

0.0000299

Gnomad4 AMR exome

AF:

0.00

Gnomad4 ASJ exome

AF:

0.00

Gnomad4 EAS exome

AF:

0.00

Gnomad4 SAS exome

AF:

0.00

Gnomad4 FIN exome

AF:

0.000131

Gnomad4 NFE exome

AF:

0.0000324

Gnomad4 OTH exome

AF:

0.0000662

GnomAD4 genome

AF:

0.0000132

AC:

AN:

152066

Hom.:

Cov.:

AF XY:

0.00

AC XY:

AN XY:

74268

show subpopulations

Gnomad4 AFR

AF:

0.00

Gnomad4 AMR

AF:

0.00

Gnomad4 ASJ

AF:

0.00

Gnomad4 EAS

AF:

0.00

Gnomad4 SAS

AF:

0.00

Gnomad4 FIN

AF:

0.00

Gnomad4 NFE

AF:

0.0000294

Gnomad4 OTH

AF:

0.00

Alfa

AF:

0.0000823

Hom.:

Bravo

AF:

0.00000756

ExAC

AF:

0.0000659

AC:

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:6

Revision: criteria provided, multiple submitters, no conflicts

LINK: link

Submissions by phenotype

Bloom syndrome

Uncertain:3

Uncertain significance, criteria provided, single submitter	clinical testing	Labcorp Genetics (formerly Invitae), Labcorp	Jan 19, 2024	This sequence change replaces arginine, which is basic and polar, with cysteine, which is neutral and slightly polar, at codon 808 of the BLM protein (p.Arg808Cys). This variant is present in population databases (rs759330541, gnomAD 0.007%). This missense change has been observed in individual(s) with early-onset, undefined familial colorectal cancer (PMID: 27356891). ClinVar contains an entry for this variant (Variation ID: 405272). Advanced modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) performed at Invitae indicates that this missense variant is expected to disrupt BLM protein function with a positive 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. -
Uncertain significance, criteria provided, single submitter	clinical testing	Fulgent Genetics, Fulgent Genetics	Apr 26, 2024	- -
Uncertain significance, no assertion criteria provided	clinical testing	Natera, Inc.	Feb 27, 2020	- -

not provided

Uncertain:2

Uncertain significance, criteria provided, single submitter	clinical testing	GeneDx	Feb 24, 2023	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; This variant is associated with the following publications: (PMID: 27356891) -
Uncertain significance, criteria provided, single submitter	clinical testing	Quest Diagnostics Nichols Institute San Juan Capistrano	Feb 13, 2024	The BLM c.2422C>T (p.Arg808Cys) variant has been reported in the published literature in an individual with early onset colorectal cancer (PMID: 27356891 (2016)). The frequency of this variant in the general population, 0.00007 (9/129154 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. -

Hereditary cancer-predisposing syndrome

Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Ambry Genetics

Apr 24, 2024

The p.R808C variant (also known as c.2422C>T), located in coding exon 11 of the BLM gene, results from a C to T substitution at nucleotide position 2422. The arginine at codon 808 is replaced by cysteine, an amino acid with highly dissimilar properties. In one study, this alteration was detected in 1/847 individuals with early-onset undefined colorectal cancer who previously tested negative for mutations in APC, MLH1, SMAD4, BMPR1A, MUTYH, MSH2, MSH6, PMS2, POLE and POLD1, and this alteration was not detected in 1609 controls (Dobbins SE et al. Fam Cancer, 2016 10;15:593-9). This amino acid position is highly conserved in available vertebrate species. In addition, the in silico prediction for this alteration is inconclusive. Based on the available evidence, the clinical significance of this variant remains unclear. -

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Pathogenic

0.99

BayesDel_addAF

Uncertain

0.12

BayesDel_noAF

Uncertain

0.11

CADD

Pathogenic

DANN

Pathogenic

1.0

DEOGEN2

Uncertain

0.52

D;.

Eigen

Pathogenic

1.0

Eigen_PC

Pathogenic

0.88

FATHMM_MKL

Pathogenic

0.97

LIST_S2

Uncertain

0.97

D;D

M_CAP

Benign

0.064

MetaRNN

Pathogenic

0.97

D;D

MetaSVM

Uncertain

0.018

MutationAssessor

Pathogenic

4.2

H;.

PrimateAI

Pathogenic

0.81

PROVEAN

Pathogenic

-7.5

D;D

REVEL

Pathogenic

0.66

Sift

Pathogenic

0.0

D;D

Sift4G

Pathogenic

0.0

D;D

Polyphen

1.0

D;.

Vest4

0.97

MutPred

0.88

Loss of MoRF binding (P = 0.0028);Loss of MoRF binding (P = 0.0028);

MVP

0.83

MPC

0.56

ClinPred

1.0

GERP RS

5.2

Varity_R

0.93

gMVP

0.88

Splicing

Name

Calibrated prediction

Score

Prediction

SpliceAI score (max)

0.020

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