chr15-90749983-G-C

Position:

chr15-90749983-G-C

Variant summary

Our verdict is Likely benign. Variant got -1 ACMG points: 2P and 3B. PM2BP4_ModerateBS1_Supporting

The NM_000057.4(BLM):c.715G>C(p.Asp239His) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.0000477 in 1,614,202 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 Uncertain significance (★★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. D239N) has been classified as Likely benign.

Frequency

Genomes: 𝑓 0.000026 ( 0 hom., cov: 32)

Exomes 𝑓: 0.000050 ( 0 hom. )

Consequence

BLM
NM_000057.4 missense

Scores

Clinical Significance

Uncertain significance criteria provided, multiple submitters, no conflicts U:4

Conservation

PhyloP100: 2.43

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:

Genome browser will be placed here

ACMG classification

Classification made for transcript

Verdict is Likely_benign. Variant got -1 ACMG points.

PM2

Very rare variant in population databases, with high coverage;

BP4

Computational evidence support a benign effect (MetaRNN=0.12342304).

BS1

Variant frequency is greater than expected in population eas. gnomad4_exome allele frequency = 0.0000499 (73/1461880) while in subpopulation EAS AF= 0.00181 (72/39696). AF 95% confidence interval is 0.00148. There are 0 homozygotes in gnomad4_exome. There are 43 alleles in male gnomad4_exome subpopulation. Median coverage is 31. This position pass quality control queck. Existence of Clinvar submissions makes me limit the strength of this signal to Supporting

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
BLM	NM_000057.4 linkuse as main transcript	c.715G>C	p.Asp239His	missense_variant	3/22	ENST00000355112.8	NP_000048.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
BLM	ENST00000355112.8 linkuse as main transcript	c.715G>C	p.Asp239His	missense_variant	3/22	1	NM_000057.4	ENSP00000347232	P2

Frequencies

GnomAD3 genomes

AF:

0.0000263

AC:

AN:

152204

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:

0.000576

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

GnomAD3 exomes

AF:

0.0000199

AC:

AN:

251016

Hom.:

AF XY:

0.0000221

AC XY:

AN XY:

135756

show subpopulations

Gnomad AFR exome

AF:

0.00

Gnomad AMR exome

AF:

0.00

Gnomad ASJ exome

AF:

0.00

Gnomad EAS exome

AF:

0.000272

Gnomad SAS 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:

0.0000499

AC:

AN:

1461880

Hom.:

Cov.:

AF XY:

0.0000591

AC XY:

AN XY:

727242

show subpopulations

Gnomad4 AFR exome

AF:

0.00

Gnomad4 AMR exome

AF:

0.00

Gnomad4 ASJ exome

AF:

0.00

Gnomad4 EAS exome

AF:

0.00181

Gnomad4 SAS exome

AF:

0.00

Gnomad4 FIN exome

AF:

0.00

Gnomad4 NFE exome

AF:

0.00

Gnomad4 OTH exome

AF:

0.0000166

GnomAD4 genome

AF:

0.0000263

AC:

AN:

152322

Hom.:

Cov.:

AF XY:

0.0000269

AC XY:

AN XY:

74474

show subpopulations

Gnomad4 AFR

AF:

0.0000240

Gnomad4 AMR

AF:

0.00

Gnomad4 ASJ

AF:

0.00

Gnomad4 EAS

AF:

0.000578

Gnomad4 SAS

AF:

0.00

Gnomad4 FIN

AF:

0.00

Gnomad4 NFE

AF:

0.00

Gnomad4 OTH

AF:

0.00

Bravo

AF:

0.0000189

ExAC

AF:

0.0000330

AC:

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:4

Revision: criteria provided, multiple submitters, no conflicts

LINK: link

Submissions by phenotype

Bloom syndrome

Uncertain:2

Uncertain significance, no assertion criteria provided	clinical testing	Natera, Inc.	Apr 23, 2020	- -
Uncertain significance, criteria provided, single submitter	clinical testing	Labcorp Genetics (formerly Invitae), Labcorp	Oct 20, 2022	This sequence change replaces aspartic acid, which is acidic and polar, with histidine, which is basic and polar, at codon 239 of the BLM protein (p.Asp239His). This variant is present in population databases (rs200756519, gnomAD 0.02%). 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: 454163). Algorithms developed to predict the effect of missense changes on protein structure and function are either unavailable or do not agree on the potential impact of this missense change (SIFT: "Tolerated"; PolyPhen-2: "Probably Damaging"; Align-GVGD: "Class C0"). 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. -

Hereditary cancer-predisposing syndrome

Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Ambry Genetics

Jan 11, 2024

The p.D239H variant (also known as c.715G>C), located in coding exon 2 of the BLM gene, results from a G to C substitution at nucleotide position 715. The aspartic acid at codon 239 is replaced by histidine, an amino acid with similar properties. In one study, this alteration was identified in a Caucasian patient with early-onset colorectal cancer (DeRycke MS et al. Mol Genet Genomic Med, 2017 Sep;5:553-569). This amino acid position is well conserved in available vertebrate species. 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. -

Hereditary breast ovarian cancer syndrome

Uncertain:1

Uncertain significance, criteria provided, single submitter

research

Cancer Genomics Group, Japanese Foundation For Cancer Research

May 01, 2019

- -

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Benign

0.15

BayesDel_addAF

Benign

-0.25

BayesDel_noAF

Benign

-0.30

CADD

Benign

DANN

Uncertain

0.99

DEOGEN2

Benign

0.22

T;.

Eigen

Benign

-0.11

Eigen_PC

Benign

-0.21

FATHMM_MKL

Benign

0.67

LIST_S2

Benign

0.82

T;T

M_CAP

Benign

0.072

MetaRNN

Benign

0.12

T;T

MetaSVM

Benign

-0.93

MutationAssessor

Uncertain

2.4

M;.

MutationTaster

Benign

1.0

N;N

PrimateAI

Benign

0.45

PROVEAN

Benign

-2.1

N;N

REVEL

Benign

0.14

Sift

Uncertain

0.0070

D;D

Sift4G

Uncertain

0.054

T;D

Polyphen

1.0

D;.

Vest4

0.33

MVP

0.86

MPC

0.48

ClinPred

0.53

GERP RS

3.6

RBP_binding_hub_radar

0.0

RBP_regulation_power_radar

1.7

Varity_R

0.12

gMVP

0.20

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