NM_000057.4:c.3163_3165delTGTinsAGC

Variant names:

• chr15-90794310-TGT-AGC
• NM_000057.4:c.3163_3165delTGTinsAGC
• BLM p.Cys1055Ser

Variant summary

Our verdict is Pathogenic. The variant received 13 ACMG points: 13P and 0B. PS1_Very_Strong PM1 PM5 PP3

The NM_000057.4(BLM):​c.3163_3165delTGTinsAGC​(p.Cys1055Ser) variant causes a missense change involving the alteration of a conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. It is difficult to determine the true allele frequency of this variant because it is of type MNV, and the frequency of such variant types in population databases may be underestimated and unreliable. No clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar. Another nucleotide change resulting in the same amino acid substitution has been previously reported as Pathogenic 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: not found (cov: 32)
• Consequence: BLM NM_000057.4 missense
• Clinical Significance: Not reported in ClinVar
• Conservation: PhyloP100: 9.73
• Publications: 0 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 13 ACMG points.

• PS1: Transcript NM_000057.4 (BLM) is affected with MISSENSE_VARIANT having same AA change as one Pathogenic present in ClinVar.
• 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
• 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: No computational evidence supports a deleterious effect, but strongly conserved according to phyloP

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.3163_3165delTGTinsAGC	p.Cys1055Ser	missense	N/A	NP_000048.1	P54132
	BLM	NM_001287246.2		c.3163_3165delTGTinsAGC	p.Cys1055Ser	missense	N/A	NP_001274175.1	P54132
	BLM	NM_001287247.2		c.3163_3165delTGTinsAGC	p.Cys1055Ser	missense	N/A	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.3163_3165delTGTinsAGC	p.Cys1055Ser	missense	N/A	ENSP00000347232.3	P54132
	BLM	ENST00000560509.5	TSL:1	c.3163_3165delTGTinsAGC	p.Cys1055Ser	missense	N/A	ENSP00000454158.1	H0YNU5
	BLM	ENST00000559724.5	TSL:1	n.*2087_*2089delTGTinsAGC		non_coding_transcript_exon	Exon 16 of 22	ENSP00000453359.1	H0YLV8

Frequencies

GnomAD3 genomes Cov.: 32

We have no GnomAD4 exomes data on this position. Probably position not covered by the project.

GnomAD4 genome Cov.: 32

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
PhyloP100		9.7

Splicing

Find out detailed SpliceAI scores and Pangolin per-transcript scores at spliceailookup.broadinstitute.org

MaxEntScan Visualizer can be used to analyze the impact of this mutation on the neighboring sequence.

Other links and lift over

hg19: chr15-91337540;