chr15-90803578-G-C

Position:

• chr15-90803578-G-C

Variant summary

Our verdict is Likely pathogenic. Variant got 6 ACMG points: 6P and 0B. PM1 PM2 PP3_Moderate

The NM_000057.4(BLM):​c.3416G>C​(p.Arg1139Pro) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.0000253 in 1,461,610 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 Conflicting classifications of pathogenicity (no stars).

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.000025 (0 hom.)
• Consequence: BLM NM_000057.4 missense
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications U:4 B:1
• Conservation: PhyloP100: 7.33

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]

ACMG classification

Verdict is Likely_pathogenic. Variant got 6 ACMG points.

• PM1: In a mutagenesis_site Decreased strongly DNA Holliday junction binding. (size 0) in uniprot entity BLM_HUMAN
• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.887

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
BLM	NM_000057.4	c.3416G>C	p.Arg1139Pro	missense_variant	18/22	ENST00000355112.8	NP_000048.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
BLM	ENST00000355112.8	c.3416G>C	p.Arg1139Pro	missense_variant	18/22	1	NM_000057.4	ENSP00000347232	P2

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD3 exomes AF: 0.0000279 AC: 7 AN: 251336 Hom.: 0 AF XY: 0.0000294 AC XY: 4 AN XY: 135836

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.00

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad SAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.0000616

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.0000253 AC: 37 AN: 1461610 Hom.: 0 Cov.: 31 AF XY: 0.0000371 AC XY: 27 AN XY: 727056

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.0000324

Gnomad4 OTH exome AF: 0.0000166

GnomAD4 genome Cov.: 32

Bravo AF: 0.00000756

ExAC AF: 0.0000247 AC: 3

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Uncertain:4 Benign:1

Revision: criteria provided, conflicting classifications

Submissions by phenotype

Hereditary cancer-predisposing syndrome Uncertain:2

Uncertain significance, criteria provided, single submitter	clinical testing	GeneKor MSA	Aug 01, 2018	- -
Uncertain significance, criteria provided, single submitter	clinical testing	Ambry Genetics	Jul 15, 2022	The p.R1139P variant (also known as c.3416G>C), located in coding exon 17 of the BLM gene, results from a G to C substitution at nucleotide position 3416. The arginine at codon 1139 is replaced by proline, an amino acid with dissimilar properties. This alteration has been reported in individuals diagnosed with breast cancer (Sokolenko AP et al. Int. J. Cancer 2012 Jun;130:2867-73; Sokolenko AP et al. Cancer Lett. 2015 Apr;359:259-61). This alteration was also reported in 1/107 Macedonian individuals with a clinical history of hereditary polyposis or hereditary non-polyposis colorectal cancer who underwent multi-gene panel testing (Staninova-Stojovska M et al. Balkan J Med Genet, 2019 Dec;22:5-16). Additionally, this alteration has been reported in 1/1197 individuals from Greece, Romania, and Turkey undergoing evaluation for inherited cancer predisposition (Tsaousis GN et al. BMC Cancer, 2019 Jun;19:535). This amino acid position is highly conserved in available vertebrate species. In addition, this alteration is predicted to be deleterious by in silico analysis. Since supporting evidence is limited at this time, the clinical significance of this alteration remains unclear. -

Bloom syndrome Uncertain:1 Benign:1

Likely benign, criteria provided, single submitter	clinical testing	Labcorp Genetics (formerly Invitae), Labcorp	Oct 16, 2023	- -
Uncertain significance, no assertion criteria provided	clinical testing	Natera, Inc.	Jul 24, 2018	- -

not provided Uncertain:1

Uncertain significance, criteria provided, single submitter

not provided

Breakthrough Genomics, Breakthrough Genomics

-

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.96
BayesDel_addAF	Pathogenic	0.18	D
BayesDel_noAF	Pathogenic	0.21
CADD	Pathogenic	28
DANN	Uncertain	1.0
DEOGEN2	Uncertain	0.44	T
Eigen	Pathogenic	0.76
Eigen_PC	Pathogenic	0.76
FATHMM_MKL	Pathogenic	0.98	D
LIST_S2	Uncertain	0.95	D
M_CAP	Benign	0.068	D
MetaRNN	Pathogenic	0.89	D
MetaSVM	Benign	-0.40	T
MutationAssessor	Pathogenic	3.5	H
MutationTaster	Benign	1.0	D;D
PrimateAI	Uncertain	0.63	T
PROVEAN	Pathogenic	-5.7	D
REVEL	Uncertain	0.55
Sift	Uncertain	0.0020	D
Sift4G	Uncertain	0.0050	D
Polyphen		0.83	P
Vest4		0.96
MutPred		0.67		Loss of MoRF binding (P = 0.0513);
MVP		0.87
MPC		0.57
ClinPred		0.93	D
GERP RS		5.7
Varity_R		0.99
gMVP		0.86

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

Other links and lift over

dbSNP: rs771776126; hg19: chr15-91346808;