rs762053925

Positions:

chr15-90751795-G-A

Variant summary

Our verdict is Uncertain significance. Variant got 0 ACMG points: 2P and 2B. PM2BP4_Moderate

The NM_000057.4(BLM):c.808G>A(p.Glu270Lys) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.0000304 in 1,611,462 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 14/21 in silico tools predict a benign outcome for this variant. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars).

Frequency

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

Exomes 𝑓: 0.000028 ( 0 hom. )

Consequence

BLM
NM_000057.4 missense

Scores

Clinical Significance

Conflicting classifications of pathogenicity criteria provided, conflicting classifications U:5B:1

Conservation

PhyloP100: 2.65

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 Uncertain_significance. Variant got 0 ACMG points.

PM2

Very rare variant in population databases, with high coverage;

BP4

Computational evidence support a benign effect (MetaRNN=0.126623).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
BLM	NM_000057.4 linkuse as main transcript	c.808G>A	p.Glu270Lys	missense_variant	4/22	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.808G>A	p.Glu270Lys	missense_variant	4/22	1	NM_000057.4	ENSP00000347232.3		P54132

Frequencies

GnomAD3 genomes

AF:

0.0000526

AC:

AN:

152120

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.0000483

Gnomad AMI

AF:

0.00

Gnomad AMR

AF:

0.000196

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:

0.000478

GnomAD3 exomes

AF:

0.0000597

AC:

AN:

251074

Hom.:

AF XY:

0.0000663

AC XY:

AN XY:

135720

show subpopulations

Gnomad AFR exome

AF:

0.00

Gnomad AMR exome

AF:

0.000116

Gnomad ASJ exome

AF:

0.00

Gnomad EAS exome

AF:

0.00

Gnomad SAS exome

AF:

0.000294

Gnomad FIN exome

AF:

0.00

Gnomad NFE exome

AF:

0.0000176

Gnomad OTH exome

AF:

0.00

GnomAD4 exome

AF:

0.0000281

AC:

AN:

1459342

Hom.:

Cov.:

AF XY:

0.0000317

AC XY:

AN XY:

726186

show subpopulations

Gnomad4 AFR exome

AF:

0.00

Gnomad4 AMR exome

AF:

0.000134

Gnomad4 ASJ exome

AF:

0.00

Gnomad4 EAS exome

AF:

0.0000757

Gnomad4 SAS exome

AF:

0.000174

Gnomad4 FIN exome

AF:

0.00

Gnomad4 NFE exome

AF:

0.00000270

Gnomad4 OTH exome

AF:

0.000216

GnomAD4 genome

AF:

0.0000526

AC:

AN:

152120

Hom.:

Cov.:

AF XY:

0.0000538

AC XY:

AN XY:

74324

show subpopulations

Gnomad4 AFR

AF:

0.0000483

Gnomad4 AMR

AF:

0.000196

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:

0.000478

Alfa

AF:

0.0000434

Hom.:

Bravo

AF:

0.0000416

ExAC

AF:

0.0000412

AC:

Asia WGS

AF:

0.00404

AC:

AN:

3478

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Uncertain:5Benign:1

Revision: criteria provided, conflicting classifications

LINK: link

Submissions by phenotype

Bloom syndrome

Uncertain:2

Uncertain significance, criteria provided, single submitter	clinical testing	Labcorp Genetics (formerly Invitae), Labcorp	Oct 05, 2022	This sequence change replaces glutamic acid, which is acidic and polar, with lysine, which is basic and polar, at codon 270 of the BLM protein (p.Glu270Lys). This variant is present in population databases (rs762053925, gnomAD 0.03%). 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: 454165). Algorithms developed to predict the effect of missense changes on protein structure and function output the following: SIFT: "Tolerated"; PolyPhen-2: "Possibly Damaging"; Align-GVGD: "Class C0". The lysine amino acid residue is found in multiple mammalian species, which suggests that this missense change does not adversely affect protein function. 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, no assertion criteria provided	clinical testing	Natera, Inc.	Nov 17, 2017	- -

not provided

Uncertain:2

Uncertain significance, criteria provided, single submitter	clinical testing	Women's Health and Genetics/Laboratory Corporation of America, LabCorp	Jul 21, 2017	Variant summary: The c.808G>A (p.Glu270Lys) in BLM gene is a missense variant involves a non-conserved nucleotide and 3/5 in silico tools predict benign outcome, however no functional studies have been published at the time of evaluation. The variant is located within the very N-terminal region of chordate domain, which exact function is not known. The variant is present at a low frequencies in the control population datasets of ExAC and gnomAD (0.00006; 5/120888 and 15/245884 chrs tested, respectively). These frequencies do not exceed the maximal expected allele frequency for a disease causing allele in BLM gene (0.0035). To our knowledge, the variant has not been reported in affected individuals via published reports nor has it been cited by reputable databases/clinical laboratories. Taken together, the variant was classified as VUS, until new information becomes available. -
Uncertain significance, criteria provided, single submitter	clinical testing	Quest Diagnostics Nichols Institute San Juan Capistrano	Feb 07, 2024	The BLM c.808G>A (p.Glu270Lys) variant has not been reported in individuals with BLM-related conditions in the published literature. The frequency of this variant in the general population, 0.00029 (9/30610 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. -

BLM-related disorder

Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

PreventionGenetics, part of Exact Sciences

Jun 02, 2023

The BLM c.808G>A variant is predicted to result in the amino acid substitution p.Glu270Lys. To our knowledge, this variant has not been reported in the literature. This variant is reported in 0.029% of alleles in individuals of South Asian descent in gnomAD (http://gnomad.broadinstitute.org/variant/15-91295025-G-A). At this time, the clinical significance of this variant is uncertain due to the absence of conclusive functional and genetic evidence. -

Hereditary cancer-predisposing syndrome

Benign:1

Likely benign, criteria provided, single submitter

clinical testing

Ambry Genetics

Feb 01, 2022

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. -

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Benign

0.066

BayesDel_addAF

Benign

-0.35

BayesDel_noAF

Benign

-0.45

CADD

Benign

DANN

Benign

0.97

DEOGEN2

Benign

0.18

T;.

Eigen

Benign

-0.35

Eigen_PC

Benign

-0.33

FATHMM_MKL

Benign

0.72

LIST_S2

Benign

0.66

T;T

M_CAP

Benign

0.027

MetaRNN

Benign

0.13

T;T

MetaSVM

Benign

-1.1

MutationAssessor

Uncertain

2.4

M;.

PrimateAI

Benign

0.40

PROVEAN

Benign

-0.51

N;N

REVEL

Benign

0.13

Sift

Benign

0.12

T;T

Sift4G

Benign

0.36

T;T

Polyphen

0.94

P;.

Vest4

0.34

MVP

0.77

MPC

0.28

ClinPred

0.12

GERP RS

4.0

Varity_R

0.037

gMVP

0.15

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