rs878853553

Positions:

• chr15-90760842-C-G

Variant summary

Our verdict is Likely benign. Variant got -1 ACMG points: 2P and 3B. PM2 BP4_Moderate BP6

The NM_000057.4(BLM):​c.1469C>G​(p.Pro490Arg) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000342 in 1,461,778 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 12/21 in silico tools predict a benign outcome for this variant. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. P490L) has been classified as Uncertain significance.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000034 (0 hom.)
• Consequence: BLM NM_000057.4 missense
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications U:2 B:1
• Conservation: PhyloP100: 0.656

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_benign. Variant got -1 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (MetaRNN=0.13697344).
• BP6: Variant 15-90760842-C-G is Benign according to our data. Variant chr15-90760842-C-G is described in ClinVar as [Conflicting_classifications_of_pathogenicity]. Clinvar id is 236802.We mark this variant Likely_benign, oryginal submissions are: {Benign=1, Uncertain_significance=2}.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
BLM	NM_000057.4	c.1469C>G	p.Pro490Arg	missense_variant	7/22	ENST00000355112.8

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
BLM	ENST00000355112.8	c.1469C>G	p.Pro490Arg	missense_variant	7/22	1	NM_000057.4	P2

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 0.00000342 AC: 5 AN: 1461778 Hom.: 0 Cov.: 32 AF XY: 0.00000275 AC XY: 2 AN XY: 727174

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.000101

Gnomad4 SAS exome AF: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00

Gnomad4 OTH exome AF: 0.0000166

GnomAD4 genome Cov.: 32

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Uncertain:2 Benign:1

Revision: criteria provided, conflicting classifications

Submissions by phenotype

Bloom syndrome Uncertain:2

Uncertain significance, criteria provided, single submitter	clinical testing	Invitae	Oct 20, 2022	In summary, the available evidence is currently insufficient to determine the role of this variant in disease. Therefore, it has been classified as a Variant of Uncertain Significance. Advanced modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) performed at Invitae indicates that this missense variant is not expected to disrupt BLM protein function. ClinVar contains an entry for this variant (Variation ID: 236802). This variant has not been reported in the literature in individuals affected with BLM-related conditions. This variant is not present in population databases (gnomAD no frequency). This sequence change replaces proline, which is neutral and non-polar, with arginine, which is basic and polar, at codon 490 of the BLM protein (p.Pro490Arg). -
Uncertain significance, criteria provided, single submitter	clinical testing	Counsyl	Mar 13, 2018	- -

not specified Benign:1

Benign, criteria provided, single submitter

clinical testing

Mendelics

May 04, 2022

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.14
BayesDel_addAF	Benign	-0.14	T
BayesDel_noAF	Benign	-0.44
CADD	Benign	16
DANN	Uncertain	0.99
DEOGEN2	Benign	0.16	T;.
Eigen	Benign	-0.75
Eigen_PC	Benign	-0.87
FATHMM_MKL	Benign	0.20	N
LIST_S2	Benign	0.75	T;T
M_CAP	Benign	0.025	D
MetaRNN	Benign	0.14	T;T
MetaSVM	Benign	-1.0	T
MutationAssessor	Uncertain	2.0	M;.
MutationTaster	Benign	1.0	N;N
PrimateAI	Benign	0.29	T
PROVEAN	Benign	-2.3	N;D
REVEL	Benign	0.055
Sift	Uncertain	0.0060	D;D
Sift4G	Benign	0.13	T;T
Polyphen		0.88	P;.
Vest4		0.22
MutPred		0.41		Gain of MoRF binding (P = 0.0026);Gain of MoRF binding (P = 0.0026);
MVP		0.83
MPC		0.16
ClinPred		0.22	T
GERP RS		0.021
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.1
Varity_R		0.066
gMVP		0.39

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: rs878853553; hg19: chr15-91304072;