NM_000057.4:c.3163T>C

Variant names:

• chr15-90794310-T-C
• rs746218707
• NM_000057.4:c.3163T>C

Variant summary

Our verdict is Pathogenic. The variant received 22 ACMG points: 22P and 0B. PS3 PM1 PM2 PM5 PP3_Strong PP5_Very_Strong

The NM_000057.4(BLM):​c.3163T>C​(p.Cys1055Arg) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.0000131 in 152,168 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 Likely pathogenic (★★). ClinVar reports functional evidence for this variant: "SCV002608498: Functional studies of p.C1055S have also demonstrated that this alteration causes reduced BLM protein expression and lacks detectable helicase and DNA-dependent ATPase activities, which are essential for wild-type interaction of BLM with tp53 in the DNA damage response pathway (Wang XW et al. J. Biol. Chem., 2001 Aug" and additional evidence is available in ClinVar. Another variant affecting the same amino acid position, but resulting in a different missense (i.e. C1055Y) has been classified as Likely pathogenic.

• Frequency: Genomes: 𝑓 0.000013 (0 hom., cov: 32)
• Consequence: BLM NM_000057.4 missense
• Clinical Significance: Likely pathogenic criteria provided, multiple submitters, no conflicts P:3 U:1
• Conservation: PhyloP100: 7.80
• Publications: 2 publications found

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: Orphanet, Labcorp Genetics (formerly Invitae), G2P, Myriad Women’s Health, Genomics England PanelApp, ClinGen, Laboratory for Molecular Medicine
• osteosarcoma

  Inheritance: AR Classification: MODERATE Submitted by: Genomics England PanelApp
• colorectal cancer

  Inheritance: AD Classification: LIMITED Submitted by: ClinGen
• breast cancer

  Inheritance: AD Classification: NO_KNOWN Submitted by: Ambry Genetics
• hereditary nonpolyposis colon cancer

  Inheritance: AD Classification: NO_KNOWN Submitted by: Ambry Genetics

ENSG00000300894 (HGNC:):

ACMG classification

Our verdict: Pathogenic. The variant received 22 ACMG points.

• PS3: PS3 evidence extracted from ClinVar submissions: SCV002608498: Functional studies of p.C1055S have also demonstrated that this alteration causes reduced BLM protein expression and lacks detectable helicase and DNA-dependent ATPase activities, which are essential for wild-type interaction of BLM with tp53 in the DNA damage response pathway (Wang XW et al. J. Biol. Chem., 2001 Aug;276:32948-55; Neff NF et al. Mol. Biol. Cell, 1999 Mar;10:665-76).
• PM1: In a helix (size 3) in uniprot entity BLM_HUMAN there are 4 pathogenic changes around while only 0 benign (100%) in NM_000057.4
• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chr15-90794311-G-A is described in ClinVar as Conflicting_classifications_of_pathogenicity. ClinVar VariationId is 803137.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.985
• PP5: Variant 15-90794310-T-C is Pathogenic according to our data. Variant chr15-90794310-T-C is described in ClinVar as Likely_pathogenic. ClinVar VariationId is 549904.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_000057.4. You can select a different transcript below to see updated ACMG assignments.

RefSeq Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	BLM	NM_000057.4	MANE Select	c.3163T>C	p.Cys1055Arg	missense	Exon 16 of 22	NP_000048.1	P54132
	BLM	NM_001287246.2		c.3163T>C	p.Cys1055Arg	missense	Exon 17 of 23	NP_001274175.1	P54132
	BLM	NM_001287247.2		c.3163T>C	p.Cys1055Arg	missense	Exon 16 of 20	NP_001274176.1	H0YNU5

Ensembl Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	BLM	ENST00000355112.8	TSL:1 MANE Select	c.3163T>C	p.Cys1055Arg	missense	Exon 16 of 22	ENSP00000347232.3	P54132
	BLM	ENST00000560509.5	TSL:1	c.3163T>C	p.Cys1055Arg	missense	Exon 16 of 20	ENSP00000454158.1	H0YNU5
	BLM	ENST00000559724.5	TSL:1	n.*2087T>C		non_coding_transcript_exon	Exon 16 of 22	ENSP00000453359.1	H0YLV8

Frequencies

GnomAD3 genomes AF: 0.0000131 AC: 2 AN: 152168 Hom.: 0 Cov.: 32

Gnomad AFR AF: 0.00

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: 0.0000294

Gnomad OTH AF: 0.00

GnomAD4 exome Cov.: 31

GnomAD4 genome AF: 0.0000131 AC: 2 AN: 152168 Hom.: 0 Cov.: 32 AF XY: 0.0000134 AC XY: 1 AN XY: 74350

African (AFR) AF: 0.00 AC: 0 AN: 41450

American (AMR) AF: 0.00 AC: 0 AN: 15278

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 3468

East Asian (EAS) AF: 0.00 AC: 0 AN: 5204

South Asian (SAS) AF: 0.00 AC: 0 AN: 4826

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 10598

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 316

European-Non Finnish (NFE) AF: 0.0000294 AC: 2 AN: 68026

Other (OTH) AF: 0.00 AC: 0 AN: 2090

Alfa AF: 0.0000361 Hom.: 0

Bravo AF: 0.00000378

ExAC AF: 0.00000824 AC: 1

ClinVar

ClinVar submissions

Significance: Likely pathogenic

Revision: criteria provided, multiple submitters, no conflicts

Pathogenic	VUS	Benign	Condition
2	1	-	Bloom syndrome (3)
1	-	-	Hereditary cancer-predisposing syndrome (1)

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.99
BayesDel_addAF	Pathogenic	0.42	D
BayesDel_noAF	Pathogenic	0.37
CADD	Pathogenic	27
DANN	Uncertain	1.0
DEOGEN2	Uncertain	0.67	D
Eigen	Pathogenic	0.90
Eigen_PC	Pathogenic	0.85
FATHMM_MKL	Pathogenic	0.98	D
LIST_S2	Uncertain	0.91	D
M_CAP	Uncertain	0.22	D
MetaRNN	Pathogenic	0.98	D
MetaSVM	Uncertain	0.48	D
MutationAssessor	Pathogenic	4.5	H
PhyloP100		7.8
PrimateAI	Pathogenic	0.79	T
PROVEAN	Pathogenic	-11	D
REVEL	Pathogenic	0.91
Sift	Uncertain	0.0020	D
Sift4G	Pathogenic	0.0	D
Polyphen		1.0	D
Vest4		0.84
MutPred		0.93		Gain of disorder (P = 0.013)
MVP		0.94
MPC		0.64
ClinPred		1.0	D
GERP RS		5.8
Varity_R		0.99
gMVP		0.94
Mutation Taster		=1/99	disease causing

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

Other links and lift over

dbSNP: rs746218707; hg19: chr15-91337540;