NM_000057.4:c.1223G>A

Variant names:

Variant summary

Our verdict is Uncertain significance. The variant received 4 ACMG points: 4P and 0B. PM1PM2

The NM_000057.4(BLM):c.1223G>A(p.Arg408Lys) variant causes a missense, splice region change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000186 in 1,609,570 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 14/24 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. R408G) has been classified as Uncertain significance.

Frequency

Genomes: 𝑓 0.0000066 ( 0 hom., cov: 32)

Exomes 𝑓: 0.0000014 ( 0 hom. )

Consequence

BLM
NM_000057.4 missense, splice_region

Scores

Clinical Significance

Uncertain significance criteria provided, multiple submitters, no conflicts U:2

Conservation

PhyloP100: 2.04

Publications

0 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: Uncertain_significance. The variant received 4 ACMG points.

PM1

In a hotspot region, there are 3 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 4 benign, 27 uncertain in NM_000057.4

PM2

Very rare variant in population databases, with high coverage;

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
BLM	NM_000057.4 link	c.1223G>A	p.Arg408Lys	missense_variant, splice_region_variant	Exon 7 of 22	ENST00000355112.8	NP_000048.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
BLM	ENST00000355112.8 link	c.1223G>A	p.Arg408Lys	missense_variant, splice_region_variant	Exon 7 of 22	1	NM_000057.4	ENSP00000347232.3

Frequencies

GnomAD3 genomes

AF:

0.00000657

AC:

AN:

152216

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.0000241

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:

0.00

Gnomad OTH

AF:

0.00

GnomAD2 exomes

AF:

0.00000402

AC:

AN:

248768

AF XY:

0.00000742

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:

0.00000886

Gnomad OTH exome

AF:

0.00

GnomAD4 exome

AF:

0.00000137

AC:

AN:

1457354

Hom.:

Cov.:

AF XY:

0.00000276

AC XY:

AN XY:

724556

show subpopulations

African (AFR)

AF:

0.00

AC:

AN:

33370

American (AMR)

AF:

0.00

AC:

AN:

44532

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

26072

East Asian (EAS)

AF:

0.00

AC:

AN:

39600

South Asian (SAS)

AF:

0.00

AC:

AN:

85886

European-Finnish (FIN)

AF:

0.00

AC:

AN:

52346

Middle Eastern (MID)

AF:

0.00

AC:

AN:

5756

European-Non Finnish (NFE)

AF:

0.00000180

AC:

AN:

1109598

Other (OTH)

AF:

0.00

AC:

AN:

60194

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.475

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

GnomAD4 genome

AF:

0.00000657

AC:

AN:

152216

Hom.:

Cov.:

AF XY:

0.0000134

AC XY:

AN XY:

74364

show subpopulations

African (AFR)

AF:

0.0000241

AC:

AN:

41454

American (AMR)

AF:

0.00

AC:

AN:

15284

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

3470

East Asian (EAS)

AF:

0.00

AC:

AN:

5198

South Asian (SAS)

AF:

0.00

AC:

AN:

4834

European-Finnish (FIN)

AF:

0.00

AC:

AN:

10620

Middle Eastern (MID)

AF:

0.00

AC:

AN:

316

European-Non Finnish (NFE)

AF:

0.00

AC:

AN:

68034

Other (OTH)

AF:

0.00

AC:

AN:

2094

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.575

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Alfa

AF:

0.0000508

Hom.:

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:2

Revision: criteria provided, multiple submitters, no conflicts

LINK: link

Submissions by phenotype

Bloom syndrome

Uncertain:1

Feb 01, 2023

Labcorp Genetics (formerly Invitae), Labcorp

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

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. Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant may disrupt the consensus splice site. Algorithms developed to predict the effect of missense changes on protein structure and function output the following: SIFT: "Tolerated"; PolyPhen-2: "Benign"; 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. ClinVar contains an entry for this variant (Variation ID: 524819). This variant has not been reported in the literature in individuals affected with BLM-related conditions. This variant is not present in population databases (gnomAD no frequency). This sequence change replaces arginine, which is basic and polar, with lysine, which is basic and polar, at codon 408 of the BLM protein (p.Arg408Lys). -

Hereditary cancer-predisposing syndrome

Uncertain:1

May 22, 2024

Ambry Genetics

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

The p.R408K variant (also known as c.1223G>A), located in coding exon 6 of the BLM gene, results from a G to A substitution at nucleotide position 1223. The arginine at codon 408 is replaced by lysine, an amino acid with highly similar properties. This amino acid position is conserved. In addition, this alteration is predicted to be tolerated by in silico analysis. 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

Benign

0.086

BayesDel_addAF

Benign

-0.18

BayesDel_noAF

Benign

-0.50

CADD

Benign

(source)

DANN

Uncertain

0.98

DEOGEN2

Benign

0.075

T;.

Eigen

Benign

0.18

Eigen_PC

Benign

0.13

FATHMM_MKL

Benign

0.75

LIST_S2

Benign

0.70

T;T

M_CAP

Benign

0.016

MetaRNN

Benign

0.35

T;T

MetaSVM

Benign

-0.91

MutationAssessor

Benign

1.8

L;.

PhyloP100

2.0

PrimateAI

Benign

0.36

PROVEAN

Benign

-0.25

N;N

REVEL

Benign

0.20

Sift

Benign

0.38

T;T

Sift4G

Benign

1.0

T;T

Polyphen

1.0

D;.

Vest4

0.18

MutPred

0.65

Loss of loop (P = 0.0112);Loss of loop (P = 0.0112);

MVP

0.85

MPC

0.14

ClinPred

0.34

GERP RS

3.0

RBP_binding_hub_radar

0.0

RBP_regulation_power_radar

1.7

Varity_R

0.20

gMVP

0.22

Mutation Taster

=71/29

polymorphism

(source)

Splicing

Name

Calibrated prediction

Score

Prediction

SpliceAI score (max)

0.24

Details are displayed if max score is > 0.2

DS_AG_spliceai

0.24

Position offset: 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

ClinVar

Submissions by phenotype

Computational scores

Splicing

Publications

Other links and lift over