rs1555424404

chr15-90804351-A-Gchr15-90804351-A-T

Variant summary

Our verdict is Uncertain significance. Variant got 0 ACMG points: 2P and 2B. PM2 BP4_Moderate

The NM_000057.4(BLM):c.3743A>G(p.Lys1248Arg) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a benign outcome for this variant. 12/20 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. K1248M) has been classified as Uncertain significance.

• Frequency: Genomes: not found (cov: 32)
• Consequence: BLM NM_000057.4 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 2.59

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 0 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (MetaRNN=0.14953542).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
BLM	NM_000057.4	c.3743A>G	p.Lys1248Arg	missense_variant	19/22	ENST00000355112.8

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
BLM	ENST00000355112.8	c.3743A>G	p.Lys1248Arg	missense_variant	19/22	1	NM_000057.4	P2

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 32

GnomAD4 genome Cov.: 32

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Hereditary cancer-predisposing syndrome Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Ambry Genetics

Oct 30, 2019

The p.K1248R variant (also known as c.3743A>G), located in coding exon 18 of the BLM gene, results from an A to G substitution at nucleotide position 3743. The lysine at codon 1248 is replaced by arginine, an amino acid with highly similar properties. This amino acid position is highly conserved in available vertebrate species. In addition, this alteration is predicted to be tolerated by in silico analysis. Since supporting evidence is limited at this time, the clinical significance of this alteration remains unclear. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.082
BayesDel_addAF	Benign	-0.22	T
BayesDel_noAF	Benign	-0.56
Cadd	Benign	19
Dann	Uncertain	0.99
DEOGEN2	Benign	0.13	T
Eigen	Benign	-0.22
Eigen_PC	Benign	-0.025
FATHMM_MKL	Uncertain	0.94	D
LIST_S2	Benign	0.79	T
M_CAP	Benign	0.0061	T
MetaRNN	Benign	0.15	T
MetaSVM	Benign	-1.1	T
MutationAssessor	Benign	0.85	L
MutationTaster	Benign	1.0	D;D
PrimateAI	Uncertain	0.61	T
PROVEAN	Benign	-1.1	N
REVEL	Benign	0.044
Sift	Benign	0.26	T
Sift4G	Benign	0.49	T
Polyphen		0.0010	B
Vest4		0.090
MutPred		0.47		Loss of helix (P = 0.0104);
MVP		0.74
MPC		0.11
ClinPred		0.84	D
GERP RS		4.9
Varity_R		0.15
gMVP		0.34

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.090		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: rs1555424404; hg19: chr15-91347581;