NM_000057.4:c.2516A>C

Variant names:

• chr15-90769547-A-C
• rs756815062
• NM_000057.4:c.2516A>C

Variant summary

Our verdict is Uncertain significance. The variant received 3 ACMG points: 4P and 1B. PM1 PM2 BP4

The NM_000057.4(BLM):​c.2516A>C​(p.Lys839Thr) variant causes a missense change. The variant allele was found at a frequency of 0.00000657 in 152,180 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 14/22 in silico tools predict a benign 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. K839E) has been classified as Likely benign.

• Frequency: Genomes: 𝑓 0.0000066 (0 hom., cov: 32)
• Consequence: BLM NM_000057.4 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:2
• Conservation: PhyloP100: 5.78
• Publications: 1 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

ACMG classification

Our verdict: Uncertain_significance. The variant received 3 ACMG points.

• PM1: In a hotspot region, there are 2 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 0 benign, 31 uncertain in NM_000057.4
• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (MetaRNN=0.37879133).

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.2516A>C	p.Lys839Thr	missense	Exon 12 of 22	NP_000048.1	P54132
	BLM	NM_001287246.2		c.2516A>C	p.Lys839Thr	missense	Exon 13 of 23	NP_001274175.1	P54132
	BLM	NM_001287247.2		c.2516A>C	p.Lys839Thr	missense	Exon 12 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.2516A>C	p.Lys839Thr	missense	Exon 12 of 22	ENSP00000347232.3	P54132
	BLM	ENST00000560509.5	TSL:1	c.2516A>C	p.Lys839Thr	missense	Exon 12 of 20	ENSP00000454158.1	H0YNU5
	BLM	ENST00000559724.5	TSL:1	n.*1440A>C		non_coding_transcript_exon	Exon 12 of 22	ENSP00000453359.1	H0YLV8

Frequencies

GnomAD3 genomes AF: 0.00000657 AC: 1 AN: 152180 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: 0.000207

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.00

Gnomad OTH AF: 0.00

GnomAD4 exome Cov.: 32

GnomAD4 genome AF: 0.00000657 AC: 1 AN: 152180 Hom.: 0 Cov.: 32 AF XY: 0.0000135 AC XY: 1 AN XY: 74346

⚠️ The allele balance in gnomAD version 4 Genomes is significantly skewed from the expected value of 0.5.

African (AFR) AF: 0.00 AC: 0 AN: 41444

American (AMR) AF: 0.00 AC: 0 AN: 15276

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

East Asian (EAS) AF: 0.00 AC: 0 AN: 5190

South Asian (SAS) AF: 0.000207 AC: 1 AN: 4828

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 10620

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

European-Non Finnish (NFE) AF: 0.00 AC: 0 AN: 68036

Other (OTH) AF: 0.00 AC: 0 AN: 2092

⚠️ The allele balance in gnomAD version 4 Genomes is significantly skewed from the expected value of 0.5. (p-value = 0), which strongly suggests a high chance of mosaicism in these individuals.

Alfa AF: 0.00 Hom.: 0

ClinVar

ClinVar submissions

Significance: Uncertain significance

Revision: criteria provided, multiple submitters, no conflicts

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

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.24
BayesDel_addAF	Benign	-0.080	T
BayesDel_noAF	Benign	-0.35
CADD	Benign	22
DANN	Uncertain	1.0
DEOGEN2	Benign	0.10	T
Eigen	Benign	-0.20
Eigen_PC	Benign	-0.041
FATHMM_MKL	Uncertain	0.96	D
LIST_S2	Uncertain	0.87	D
M_CAP	Benign	0.028	D
MetaRNN	Benign	0.38	T
MetaSVM	Benign	-1.1	T
MutationAssessor	Benign	1.4	L
PhyloP100		5.8
PrimateAI	Uncertain	0.71	T
PROVEAN	Benign	-1.7	N
REVEL	Benign	0.063
Sift	Benign	0.22	T
Sift4G	Benign	0.29	T
Polyphen		0.0070	B
Vest4		0.47
MutPred		0.45		Loss of MoRF binding (P = 0.0367)
MVP		0.79
MPC		0.15
ClinPred		0.71	D
GERP RS		3.7
Varity_R		0.53
gMVP		0.80

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: rs756815062; hg19: chr15-91312777;