rs28903082

Variant summary

Our verdict is Benign. The variant received -21 ACMG points: 0P and 21B. BP4_StrongBP6_Very_StrongBP7BS1BS2

The NM_000057.4(BLM):​c.615G>A​(p.Lys205Lys) variant causes a synonymous change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000863 in 1,611,530 control chromosomes in the GnomAD database, including 9 homozygotes. In-silico tool predicts a benign outcome for this variant. Variant has been reported in ClinVar as Likely benign (★★).

Frequency

Genomes: 𝑓 0.0045 ( 7 hom., cov: 32)
Exomes 𝑓: 0.00049 ( 2 hom. )

Consequence

BLM
NM_000057.4 synonymous

Scores

2

Clinical Significance

Benign/Likely benign criteria provided, multiple submitters, no conflicts B:9

Conservation

PhyloP100: 1.14
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]

Genome browser will be placed here

ACMG classification

Classification was made for transcript

Our verdict: Benign. The variant received -21 ACMG points.

BP4
Computational evidence support a benign effect (BayesDel_noAF=-0.78).
BP6
Variant 15-90749883-G-A is Benign according to our data. Variant chr15-90749883-G-A is described in ClinVar as [Likely_benign]. Clinvar id is 136509.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.
BP7
Synonymous conserved (PhyloP=1.14 with no splicing effect.
BS1
Variant frequency is greater than expected in population afr. GnomAd4 allele frequency = 0.00448 (682/152266) while in subpopulation AFR AF = 0.0156 (648/41548). AF 95% confidence interval is 0.0146. There are 7 homozygotes in GnomAd4. There are 312 alleles in the male GnomAd4 subpopulation. Median coverage is 32. This position passed quality control check.
BS2
High Homozygotes in GnomAd4 at 7 AR,AD gene

Transcripts

RefSeq

Gene Transcript HGVSc HGVSp Effect Exon rank MANE Protein UniProt
BLMNM_000057.4 linkc.615G>A p.Lys205Lys synonymous_variant Exon 3 of 22 ENST00000355112.8 NP_000048.1 P54132

Ensembl

Gene Transcript HGVSc HGVSp Effect Exon rank TSL MANE Protein Appris UniProt
BLMENST00000355112.8 linkc.615G>A p.Lys205Lys synonymous_variant Exon 3 of 22 1 NM_000057.4 ENSP00000347232.3 P54132

Frequencies

GnomAD3 genomes
AF:
0.00450
AC:
684
AN:
152148
Hom.:
7
Cov.:
32
show subpopulations
Gnomad AFR
AF:
0.0157
Gnomad AMI
AF:
0.00
Gnomad AMR
AF:
0.00177
Gnomad ASJ
AF:
0.00
Gnomad EAS
AF:
0.00
Gnomad SAS
AF:
0.000207
Gnomad FIN
AF:
0.00
Gnomad MID
AF:
0.00
Gnomad NFE
AF:
0.0000147
Gnomad OTH
AF:
0.00239
GnomAD2 exomes
AF:
0.00128
AC:
320
AN:
250338
AF XY:
0.000768
show subpopulations
Gnomad AFR exome
AF:
0.0176
Gnomad AMR exome
AF:
0.000698
Gnomad ASJ exome
AF:
0.00
Gnomad EAS exome
AF:
0.00
Gnomad FIN exome
AF:
0.00
Gnomad NFE exome
AF:
0.0000618
Gnomad OTH exome
AF:
0.000329
GnomAD4 exome
AF:
0.000485
AC:
708
AN:
1459264
Hom.:
2
Cov.:
31
AF XY:
0.000396
AC XY:
287
AN XY:
725500
show subpopulations
African (AFR)
AF:
0.0177
AC:
589
AN:
33340
American (AMR)
AF:
0.000629
AC:
28
AN:
44500
Ashkenazi Jewish (ASJ)
AF:
0.00
AC:
0
AN:
26048
East Asian (EAS)
AF:
0.00
AC:
0
AN:
39648
South Asian (SAS)
AF:
0.0000348
AC:
3
AN:
86122
European-Finnish (FIN)
AF:
0.00
AC:
0
AN:
53370
Middle Eastern (MID)
AF:
0.000869
AC:
5
AN:
5756
European-Non Finnish (NFE)
AF:
0.0000198
AC:
22
AN:
1110186
Other (OTH)
AF:
0.00101
AC:
61
AN:
60294
Allele Balance Distribution
Red line indicates average allele balance
Average allele balance: 0.480
Heterozygous variant carriers
0
46
93
139
186
232
0.00
0.20
0.40
0.60
0.80
0.95
Allele balance

Age Distribution

Exome Het
Exome Hom
Variant carriers
0
22
44
66
88
110
<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:
0.00448
AC:
682
AN:
152266
Hom.:
7
Cov.:
32
AF XY:
0.00419
AC XY:
312
AN XY:
74442
show subpopulations
African (AFR)
AF:
0.0156
AC:
648
AN:
41548
American (AMR)
AF:
0.00177
AC:
27
AN:
15292
Ashkenazi Jewish (ASJ)
AF:
0.00
AC:
0
AN:
3472
East Asian (EAS)
AF:
0.00
AC:
0
AN:
5190
South Asian (SAS)
AF:
0.000207
AC:
1
AN:
4826
European-Finnish (FIN)
AF:
0.00
AC:
0
AN:
10612
Middle Eastern (MID)
AF:
0.00
AC:
0
AN:
294
European-Non Finnish (NFE)
AF:
0.0000147
AC:
1
AN:
68006
Other (OTH)
AF:
0.00237
AC:
5
AN:
2114
Allele Balance Distribution
Red line indicates average allele balance
Average allele balance: 0.493
Heterozygous variant carriers
0
34
68
102
136
170
0.00
0.20
0.40
0.60
0.80
0.95
Allele balance

Age Distribution

Genome Het
Variant carriers
0
10
20
30
40
50
<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:
0.00267
Hom.:
1
Bravo
AF:
0.00494
Asia WGS
AF:
0.000289
AC:
1
AN:
3478

ClinVar

Significance: Benign/Likely benign
Submissions summary: Benign:9
Revision: criteria provided, multiple submitters, no conflicts
LINK: link

Submissions by phenotype

not specified Benign:4
Apr 25, 2019
Genetic Services Laboratory, University of Chicago
Significance:Benign
Review Status:criteria provided, single submitter
Collection Method:clinical testing

- -

Jan 06, 2014
GeneDx
Significance:Benign
Review Status:criteria provided, single submitter
Collection Method:clinical testing

This variant is considered likely benign or benign based on one or more of the following criteria: it is a conservative change, it occurs at a poorly conserved position in the protein, it is predicted to be benign by multiple in silico algorithms, and/or has population frequency not consistent with disease. -

May 17, 2021
Quest Diagnostics Nichols Institute San Juan Capistrano
Significance:Benign
Review Status:criteria provided, single submitter
Collection Method:clinical testing

- -

Aug 13, 2018
Women's Health and Genetics/Laboratory Corporation of America, LabCorp
Significance:Benign
Review Status:criteria provided, single submitter
Collection Method:clinical testing

Variant summary: BLM c.615G>A alters a non-conserved nucleotide resulting in a synonymous change. 5/5 computational tools predict no significant impact on normal splicing. However, these predictions have yet to be confirmed by functional studies. The variant allele was found at a frequency of 0.0016 in 276156 control chromosomes, predominantly within the African subpopulation at a frequency of 0.017 in the gnomAD database, including 3 homozygotes. The observed variant frequency within African control individuals in the gnomAD database is approximately 4.8 fold of the estimated maximal expected allele frequency for a pathogenic variant in BLM causing Bloom Syndrome phenotype (0.0035), strongly suggesting that the variant is a benign polymorphism found primarily in populations of African origin. To our knowledge, no occurrence of c.615G>A in individuals affected with Bloom Syndrome and no experimental evidence demonstrating its impact on protein function have been reported. Three clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar after 2014 without evidence for independent evaluation. All laboratories classified the variant as benign/likely benign. Based on the evidence outlined above, the variant was classified as benign. -

Bloom syndrome Benign:3
Jul 07, 2023
KCCC/NGS Laboratory, Kuwait Cancer Control Center
Significance:Benign
Review Status:criteria provided, single submitter
Collection Method:clinical testing

- -

Feb 03, 2025
Labcorp Genetics (formerly Invitae), Labcorp
Significance:Benign
Review Status:criteria provided, single submitter
Collection Method:clinical testing

- -

Apr 25, 2017
Natera, Inc.
Significance:Likely benign
Review Status:no assertion criteria provided
Collection Method:clinical testing

- -

not provided Benign:1
-
Breakthrough Genomics, Breakthrough Genomics
Significance:Likely benign
Review Status:criteria provided, single submitter
Collection Method:not provided

- -

Hereditary cancer-predisposing syndrome Benign:1
Nov 25, 2016
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 v4.3

Name
Calibrated prediction
Score
Prediction
BayesDel_noAF
Benign
-0.78
CADD
Benign
6.7
DANN
Benign
0.60
PhyloP100
1.1
Mutation Taster
=100/0
polymorphism

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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Other links and lift over

dbSNP: rs28903082; hg19: chr15-91293113; API