rs1474290499

Variant summary

Our verdict is Uncertain significance. The variant received 5 ACMG points: 5P and 0B. PM1PM2PP3

The NM_000057.4(BLM):​c.2213C>G​(p.Thr738Arg) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000658 in 152,030 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic 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. T738I) has been classified as Uncertain significance.

Frequency

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

Consequence

BLM
NM_000057.4 missense

Scores

5
8
5

Clinical Significance

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

Conservation

PhyloP100: 7.25

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

Genome browser will be placed here

ACMG classification

Classification was made for transcript

Our verdict: Uncertain_significance. The variant received 5 ACMG points.

PM1
In a hotspot region, there are 4 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 1 benign, 24 uncertain in NM_000057.4
PM2
Very rare variant in population databases, with high coverage;
PP3
MetaRNN computational evidence supports a deleterious effect, 0.819

Transcripts

RefSeq

Gene Transcript HGVSc HGVSp Effect Exon rank MANE Protein UniProt
BLMNM_000057.4 linkc.2213C>G p.Thr738Arg missense_variant Exon 10 of 22 ENST00000355112.8 NP_000048.1

Ensembl

Gene Transcript HGVSc HGVSp Effect Exon rank TSL MANE Protein Appris UniProt
BLMENST00000355112.8 linkc.2213C>G p.Thr738Arg missense_variant Exon 10 of 22 1 NM_000057.4 ENSP00000347232.3

Frequencies

GnomAD3 genomes
AF:
0.00000658
AC:
1
AN:
152030
Hom.:
0
Cov.:
32
show subpopulations
Gnomad AFR
AF:
0.00
Gnomad AMI
AF:
0.00
Gnomad AMR
AF:
0.0000656
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
GnomAD4 exome
Cov.:
29
GnomAD4 genome
AF:
0.00000658
AC:
1
AN:
152030
Hom.:
0
Cov.:
32
AF XY:
0.00
AC XY:
0
AN XY:
74256
show subpopulations
African (AFR)
AF:
0.00
AC:
0
AN:
41386
American (AMR)
AF:
0.0000656
AC:
1
AN:
15254
Ashkenazi Jewish (ASJ)
AF:
0.00
AC:
0
AN:
3472
East Asian (EAS)
AF:
0.00
AC:
0
AN:
5196
South Asian (SAS)
AF:
0.00
AC:
0
AN:
4832
European-Finnish (FIN)
AF:
0.00
AC:
0
AN:
10562
Middle Eastern (MID)
AF:
0.00
AC:
0
AN:
316
European-Non Finnish (NFE)
AF:
0.00
AC:
0
AN:
68010
Other (OTH)
AF:
0.00
AC:
0
AN:
2090
Allele Balance Distribution
Red line indicates average allele balance
Average allele balance: 0.525
Heterozygous variant carriers
0
0
1
1
2
2
0.00
0.20
0.40
0.60
0.80
0.95
Allele balance
Alfa
AF:
0.00
Hom.:
0
Bravo
AF:
0.00000378

ClinVar

Significance: Uncertain significance
Submissions summary: Uncertain:2
Revision: criteria provided, multiple submitters, no conflicts
LINK: link

Submissions by phenotype

Bloom syndrome Uncertain:1
May 27, 2024
Labcorp Genetics (formerly Invitae), Labcorp
Significance:Uncertain significance
Review Status:criteria provided, single submitter
Collection Method:clinical testing

This sequence change replaces threonine, which is neutral and polar, with arginine, which is basic and polar, at codon 738 of the BLM protein (p.Thr738Arg). This variant is not present in population databases (gnomAD no frequency). 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: 524803). Advanced modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) performed at Invitae indicates that this missense variant is expected to disrupt BLM protein function with a positive 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.

Hereditary cancer-predisposing syndrome Uncertain:1
Jan 17, 2024
Ambry Genetics
Significance:Uncertain significance
Review Status:criteria provided, single submitter
Collection Method:clinical testing

The p.T738R variant (also known as c.2213C>G), located in coding exon 9 of the BLM gene, results from a C to G substitution at nucleotide position 2213. The threonine at codon 738 is replaced by arginine, an amino acid with similar properties. This amino acid position is conserved. In addition, the in silico prediction for this alteration is inconclusive. 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
Pathogenic
0.95
BayesDel_addAF
Uncertain
0.045
T
BayesDel_noAF
Benign
-0.17
CADD
Pathogenic
28
DANN
Uncertain
1.0
DEOGEN2
Benign
0.34
T;.
Eigen
Pathogenic
0.80
Eigen_PC
Pathogenic
0.80
FATHMM_MKL
Pathogenic
0.98
D
LIST_S2
Uncertain
0.94
D;D
M_CAP
Benign
0.029
D
MetaRNN
Pathogenic
0.82
D;D
MetaSVM
Benign
-1.1
T
MutationAssessor
Benign
1.7
L;.
PhyloP100
7.3
PrimateAI
Uncertain
0.75
T
PROVEAN
Uncertain
-3.3
D;D
REVEL
Uncertain
0.39
Sift
Uncertain
0.0040
D;D
Sift4G
Uncertain
0.011
D;D
Vest4
0.77
ClinPred
0.98
D
GERP RS
5.7
Varity_R
0.92
gMVP
0.81

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

Other links and lift over

dbSNP: rs1474290499; hg19: chr15-91310159; API