dbSNP rs538728271: BLM:p.Glu399Lys (chr15-90760254-G-A) – ACMG Classification: Benign (-7 pts)

Variant summary

Our verdict is Benign. The variant received -7 ACMG points: 2P and 9B. PM1BP4_StrongBP6BS1

The NM_000057.4(BLM):c.1195G>A(p.Glu399Lys) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.0000613 in 1,613,892 control chromosomes in the GnomAD database, including 1 homozygotes. 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 Conflicting classifications of pathogenicity (no stars). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. E399Q) has been classified as Uncertain significance.

Frequency

Genomes: 𝑓 0.000013 ( 0 hom., cov: 32)

Exomes 𝑓: 0.000066 ( 1 hom. )

Consequence

BLM
NM_000057.4 missense

Scores

Clinical Significance

Conflicting classifications of pathogenicity criteria provided, conflicting classifications U:3B:1

Conservation

PhyloP100: 2.67

Publications

1 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: Benign. The variant received -7 ACMG points.

PM1

In a hotspot region, there are 2 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 4 benign, 23 uncertain in NM_000057.4

BP4

Computational evidence support a benign effect (MetaRNN=0.0463714).

BP6

Variant 15-90760254-G-A is Benign according to our data. Variant chr15-90760254-G-A is described in ClinVar as Conflicting_classifications_of_pathogenicity. ClinVar VariationId is 485334.

BS1

Variant frequency is greater than expected in population sas. GnomAdExome4 allele frequency = 0.0000664 (97/1461798) while in subpopulation SAS AF = 0.00103 (89/86242). AF 95% confidence interval is 0.000858. There are 1 homozygotes in GnomAdExome4. There are 71 alleles in the male GnomAdExome4 subpopulation. Median coverage is 33. This position passed quality control check.

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_000057.4. You can select a different transcript below to see updated ACMG assignments.

RefSeq Transcripts

Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein
BLM	NM_000057.4	MANE Select	c.1195G>A	p.Glu399Lys	missense	Exon 6 of 22	NP_000048.1
BLM	NM_001287246.2		c.1195G>A	p.Glu399Lys	missense	Exon 7 of 23	NP_001274175.1
BLM	NM_001287247.2		c.1195G>A	p.Glu399Lys	missense	Exon 6 of 20	NP_001274176.1

Ensembl Transcripts

Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein
BLM	ENST00000355112.8	TSL:1 MANE Select	c.1195G>A	p.Glu399Lys	missense	Exon 6 of 22	ENSP00000347232.3
BLM	ENST00000560509.5	TSL:1	c.1195G>A	p.Glu399Lys	missense	Exon 6 of 20	ENSP00000454158.1
BLM	ENST00000559724.5	TSL:1	n.*119G>A		non_coding_transcript_exon	Exon 6 of 22	ENSP00000453359.1

Frequencies

GnomAD3 genomes

AF:

0.0000131

AC:

AN:

152094

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:

0.000414

Gnomad FIN

AF:

0.00

Gnomad MID

AF:

0.00

Gnomad NFE

AF:

0.00

Gnomad OTH

AF:

0.00

GnomAD2 exomes

AF:

0.000135

AC:

AN:

251436

AF XY:

0.000184

show subpopulations

Gnomad AFR exome

AF:

0.00

Gnomad AMR exome

AF:

0.00

Gnomad ASJ exome

AF:

0.00

Gnomad EAS exome

AF:

0.0000544

Gnomad FIN exome

AF:

0.00

Gnomad NFE exome

AF:

0.00

Gnomad OTH exome

AF:

0.00

GnomAD4 exome

AF:

0.0000664

AC:

AN:

1461798

Hom.:

Cov.:

AF XY:

0.0000976

AC XY:

AN XY:

727202

show subpopulations

African (AFR)

AF:

0.00

AC:

AN:

33476

American (AMR)

AF:

0.00

AC:

AN:

44722

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

26134

East Asian (EAS)

AF:

0.0000252

AC:

AN:

39686

South Asian (SAS)

AF:

0.00103

AC:

AN:

86242

European-Finnish (FIN)

AF:

0.00

AC:

AN:

53414

Middle Eastern (MID)

AF:

0.00

AC:

AN:

5764

European-Non Finnish (NFE)

AF:

0.00000540

AC:

AN:

1111968

Other (OTH)

AF:

0.0000166

AC:

AN:

60392

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.478

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Age Distribution

Exome Het

Exome Hom

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:

0.0000131

AC:

AN:

152094

Hom.:

Cov.:

AF XY:

0.0000135

AC XY:

AN XY:

74304

show subpopulations

African (AFR)

AF:

0.00

AC:

AN:

41414

American (AMR)

AF:

0.00

AC:

AN:

15264

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

3470

East Asian (EAS)

AF:

0.00

AC:

AN:

5198

South Asian (SAS)

AF:

0.000414

AC:

AN:

4826

European-Finnish (FIN)

AF:

0.00

AC:

AN:

10580

Middle Eastern (MID)

AF:

0.00

AC:

AN:

316

European-Non Finnish (NFE)

AF:

0.00

AC:

AN:

68022

Other (OTH)

AF:

0.00

AC:

AN:

2092

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.525

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:

0.0000386

Hom.:

Bravo

AF:

0.0000189

ExAC

AF:

0.000173

AC:

Asia WGS

AF:

0.000577

AC:

AN:

3478

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Uncertain:3Benign:1

Revision: criteria provided, conflicting classifications

LINK: link

Submissions by phenotype

Bloom syndrome

Uncertain:2

Oct 31, 2018

Fulgent Genetics, Fulgent Genetics

Significance:Uncertain significance

Review Status:criteria provided, single submitter

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 glutamic acid, which is acidic and polar, with lysine, which is basic and polar, at codon 399 of the BLM protein (p.Glu399Lys). This variant is present in population databases (rs538728271, gnomAD 0.1%). 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: 485334). 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.

not provided

Uncertain:1

May 12, 2021

Quest Diagnostics Nichols Institute San Juan Capistrano

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

Hereditary cancer-predisposing syndrome

Benign:1

Sep 01, 2022

Ambry Genetics

Significance:Likely benign

Review Status:criteria provided, single submitter

Collection Method:clinical testing

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 v4.9

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Benign

0.088

BayesDel_addAF

Benign

-0.46

BayesDel_noAF

Benign

-0.48

CADD

Benign

(source)

DANN

Uncertain

0.98

DEOGEN2

Benign

0.23

Eigen

Benign

-0.51

Eigen_PC

Benign

-0.44

FATHMM_MKL

Uncertain

0.77

LIST_S2

Benign

0.82

M_CAP

Benign

0.013

MetaRNN

Benign

0.046

MetaSVM

Benign

-1.0

MutationAssessor

Benign

1.7

PhyloP100

2.7

PrimateAI

Benign

0.30

PROVEAN

Benign

-0.79

REVEL

Benign

0.051

Sift

Benign

0.12

Sift4G

Benign

0.34

Polyphen

0.044

Vest4

0.21

MutPred

0.62

Gain of MoRF binding (P = 0.0038)

MVP

0.77

MPC

0.11

ClinPred

0.039

GERP RS

0.37

Varity_R

0.22

gMVP

0.32

Mutation Taster

=77/23

polymorphism

(source)

Splicing

Name

Calibrated prediction

Score

Prediction

SpliceAI score (max)

0.070

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

Variant Effect in Transcripts

RefSeq Transcripts

Ensembl Transcripts

Frequencies

Age Distribution

Age Distribution

ClinVar

Submissions by phenotype

Computational scores

Splicing

Publications

Other links and lift over