rs769184675

Variant names:

• chr15-90769429-TC-T
• rs769184675
• NM_000057.4:c.2407-7delC

Variant summary

Our verdict is Uncertain significance. Variant got 2 ACMG points: 2P and 0B. PM2

The NM_000057.4(BLM):​c.2407-7delC variant causes a splice region, intron change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000013 in 1,614,044 control chromosomes in the GnomAD database, with no homozygous occurrence. 1/1 splice prediction tools predict no significant impact on normal splicing. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars).

• Frequency:
  • Genomes: 𝑓 0.000079 (0 hom., cov: 32)
  • Exomes 𝑓: 0.0000062 (0 hom.)
• Consequence: BLM NM_000057.4 splice_region, intron
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications U:4 B:1
• Conservation: PhyloP100: 0.133

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 Uncertain_significance. Variant got 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	c.2407-7delC		splice_region_variant, intron_variant	Intron 11 of 21	ENST00000355112.8	NP_000048.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
BLM	ENST00000355112.8	c.2407-8delC		splice_region_variant, intron_variant	Intron 11 of 21	1	NM_000057.4	ENSP00000347232.3

Frequencies

GnomAD3 genomes AF: 0.0000788 AC: 12 AN: 152212 Hom.: 0 Cov.: 32

Gnomad AFR AF: 0.000290

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.00

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

GnomAD3 exomes AF: 0.0000159 AC: 4 AN: 251312 Hom.: 0 AF XY: 0.00000736 AC XY: 1 AN XY: 135856

Gnomad AFR exome AF: 0.000247

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: 0.00

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000616 AC: 9 AN: 1461832 Hom.: 0 Cov.: 32 AF XY: 0.00000550 AC XY: 4 AN XY: 727220

Gnomad4 AFR exome AF: 0.000239

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: 8.99e-7

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome AF: 0.0000788 AC: 12 AN: 152212 Hom.: 0 Cov.: 32 AF XY: 0.0000672 AC XY: 5 AN XY: 74362

Gnomad4 AFR AF: 0.000290

Gnomad4 AMR AF: 0.00

Gnomad4 ASJ AF: 0.00

Gnomad4 EAS AF: 0.00

Gnomad4 SAS AF: 0.00

Gnomad4 FIN AF: 0.00

Gnomad4 NFE AF: 0.00

Gnomad4 OTH AF: 0.00

Alfa AF: 0.0000712 Hom.: 0

Bravo AF: 0.000106

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Uncertain:4 Benign:1

Revision: criteria provided, conflicting classifications

Submissions by phenotype

Bloom syndrome Uncertain:2 Benign:1

Jan 11, 2025

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Benign

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Nov 16, 2017

Natera, Inc.

Significance: Uncertain significance

Review Status: no assertion criteria provided

Collection Method: clinical testing

- -

Jun 05, 2017

Counsyl

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

not specified Uncertain:1

Mar 10, 2020

Genetic Services Laboratory, University of Chicago

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

DNA sequence analysis of the BLM gene demonstrated a sequence change in intron 11, c.2407-7del. This change does not appear to have been previously described in patients with BLM-related disorders and has been described in the gnomAD database in eight individuals (dbSNP rs749544427). In silico splice site prediction programs give conflicting results on the effect on splicing of this variant. The functional significance of this sequence change is not known at present and its contribution to a disease phenotype cannot definitively be determined. -

not provided Uncertain:1

Jul 02, 2024

GeneDx

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

In silico analysis indicates that this variant does not alter splicing; Has not been previously published as pathogenic or benign to our knowledge -

Computational scores

Source: dbNSFP v4.3

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.020		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: rs769184675; hg19: chr15-91312659;