Genetic Variant BLM:p.Thr1015Arg (chr15-90794191-C-G) – ACMG Classification: Uncertain_significance (2 pts)

Variant summary

Our verdict is Uncertain significance. The variant received 2 ACMG points: 2P and 0B. PM2

The NM_000057.4(BLM):c.3044C>G(p.Thr1015Arg) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000125 in 1,604,652 control chromosomes in the GnomAD database, with no homozygous occurrence. No clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar. Another variant affecting the same amino acid position, but resulting in a different missense (i.e. T1015A) has been classified as Uncertain significance.

Frequency

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

Exomes 𝑓: 6.9e-7 ( 0 hom. )

Consequence

BLM
NM_000057.4 missense

Scores

Clinical Significance

Not reported in ClinVar

Conservation

PhyloP100: 7.36

Publications

6 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:

ENSG00000300894 (HGNC:):

ENSG00000300894 links:

Genome browser will be placed here

ACMG classification

Classification was made for transcript

Our verdict: Uncertain_significance. The variant received 2 ACMG points.

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.3044C>G	p.Thr1015Arg	missense_variant	Exon 16 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.3044C>G	p.Thr1015Arg	missense_variant	Exon 16 of 22	1	NM_000057.4	ENSP00000347232.3		P54132

Frequencies

GnomAD3 genomes

AF:

0.00000658

AC:

AN:

152048

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.00

Gnomad AMI

AF:

0.00

Gnomad AMR

AF:

0.0000655

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:

248866

AF XY:

0.00

show subpopulations

Gnomad AFR exome

AF:

0.00

Gnomad AMR exome

AF:

0.0000294

Gnomad ASJ exome

AF:

0.00

Gnomad EAS exome

AF:

0.00

Gnomad FIN exome

AF:

0.00

Gnomad NFE exome

AF:

0.00

Gnomad OTH exome

AF:

0.00

GnomAD4 exome

AF:

6.88e-7

AC:

AN:

1452486

Hom.:

Cov.:

AF XY:

0.00

AC XY:

AN XY:

722694

show subpopulations

⚠️ The allele balance in gnomAD version 4 Exomes is significantly skewed from the expected value of 0.5.

African (AFR)

AF:

0.00

AC:

AN:

33320

American (AMR)

AF:

0.00

AC:

AN:

44208

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

25998

East Asian (EAS)

AF:

0.00

AC:

AN:

39230

South Asian (SAS)

AF:

0.00

AC:

AN:

84880

European-Finnish (FIN)

AF:

0.00

AC:

AN:

53094

Middle Eastern (MID)

AF:

0.00

AC:

AN:

5734

European-Non Finnish (NFE)

AF:

9.04e-7

AC:

AN:

1106068

Other (OTH)

AF:

0.00

AC:

AN:

59954

⚠️ The allele balance in gnomAD4 Exomes is highly skewed from 0.5 (p-value = 0), which strongly suggests a high chance of mosaicism in these individuals.

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.325

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Age Distribution

Exome 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

GnomAD4 genome

AF:

0.00000657

AC:

AN:

152166

Hom.:

Cov.:

AF XY:

0.00

AC XY:

AN XY:

74410

show subpopulations

African (AFR)

AF:

0.00

AC:

AN:

41526

American (AMR)

AF:

0.0000654

AC:

AN:

15290

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

3472

East Asian (EAS)

AF:

0.00

AC:

AN:

5182

South Asian (SAS)

AF:

0.00

AC:

AN:

4814

European-Finnish (FIN)

AF:

0.00

AC:

AN:

10560

Middle Eastern (MID)

AF:

0.00

AC:

AN:

294

European-Non Finnish (NFE)

AF:

0.00

AC:

AN:

68004

Other (OTH)

AF:

0.00

AC:

AN:

2114

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

ExAC

AF:

0.00000824

AC:

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Pathogenic

0.76

BayesDel_addAF

Pathogenic

0.20

BayesDel_noAF

Uncertain

0.050

CADD

Uncertain

(source)

DANN

Uncertain

0.99

DEOGEN2

Benign

0.35

T;.

Eigen

Benign

0.052

Eigen_PC

Uncertain

0.25

FATHMM_MKL

Pathogenic

1.0

LIST_S2

Uncertain

0.90

D;D

M_CAP

Benign

0.034

MetaRNN

Uncertain

0.45

T;T

MetaSVM

Benign

-0.71

MutationAssessor

Benign

0.57

N;.

PhyloP100

7.4

PrimateAI

Uncertain

0.57

PROVEAN

Uncertain

-4.1

D;D

REVEL

Uncertain

0.41

Sift

Uncertain

0.0030

D;D

Sift4G

Uncertain

0.0060

D;D

Polyphen

0.030

B;.

Vest4

0.74

MutPred

0.22

Gain of phosphorylation at T1018 (P = 0.0767);Gain of phosphorylation at T1018 (P = 0.0767);

MVP

0.88

MPC

0.50

ClinPred

0.97

GERP RS

5.5

Varity_R

0.80

gMVP

0.72

Mutation Taster

=55/45

polymorphism

(source)

Splicing

Name

Calibrated prediction

Score

Prediction

SpliceAI score (max)

0.010

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

Transcripts

RefSeq

Ensembl

Frequencies

Age Distribution

ClinVar

Computational scores

Splicing

Publications

Other links and lift over