16-58019056-G-T

Variant names:

• chr16-58019056-G-T
• rs1292827495
• NM_024598.4:c.693+1G>T

Variant summary

Our verdict is Likely pathogenic. Variant got 8 ACMG points: 8P and 0B. PVS1_Strong PM2 PP5_Moderate

The NM_024598.4(USB1):​c.693+1G>T variant causes a splice donor, intron change. The variant allele was found at a frequency of 0.0000178 in 1,461,808 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. 3/3 splice prediction tools predicting alterations to normal splicing. Variant has been reported in ClinVar as Pathogenic (★).

• Frequency:
  • Genomes: not found (cov: 31)
  • Exomes 𝑓: 0.000018 (0 hom.)
• Consequence: USB1 NM_024598.4 splice_donor, intron
• Scores: Splicing: ADA: 1.000
• Clinical Significance: Pathogenic criteria provided, single submitter P:1 O:1
• Conservation: PhyloP100: 6.36

Genes affected

USB1 (HGNC:25792): (U6 snRNA biogenesis phosphodiesterase 1) This gene encodes a protein with several conserved domains, however, its exact function is not known. Mutations in this gene are associated with poikiloderma with neutropenia (PN), which shows phenotypic overlap with Rothmund-Thomson syndrome (RTS) caused by mutations in the RECQL4 gene. It is believed that this gene product interacts with RECQL4 protein via SMAD4 proteins, explaining the partial clinical overlap between PN and RTS. Alternatively spliced transcript variants encoding different isoforms have been noted for this gene. [provided by RefSeq, Mar 2011]

ACMG classification

Verdict is Likely_pathogenic. Variant got 8 ACMG points.

• PVS1: Splicing +-2 bp (donor or acceptor) variant, product NOT destroyed by NMD, known LOF gene, truncates exone, which is 0.10526316 fraction of the gene. No cryptic splice site detected. Exon removal is inframe change.
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 16-58019056-G-T is Pathogenic according to our data. Variant chr16-58019056-G-T is described in ClinVar as [Pathogenic]. Clinvar id is 496749.Status of the report is criteria_provided_single_submitter, 1 stars. Variant chr16-58019056-G-T is described in Lovd as [Likely_pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
USB1	NM_024598.4	c.693+1G>T		splice_donor_variant, intron_variant	Intron 6 of 6	ENST00000219281.8	NP_078874.2
USB1	NM_001195302.2	c.639+1G>T		splice_donor_variant, intron_variant	Intron 5 of 5		NP_001182231.1
USB1	NM_001330568.2	c.540+1G>T		splice_donor_variant, intron_variant	Intron 6 of 6		NP_001317497.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
USB1	ENST00000219281.8	c.693+1G>T		splice_donor_variant, intron_variant	Intron 6 of 6	1	NM_024598.4	ENSP00000219281.3

Frequencies

GnomAD3 genomes Cov.: 31

GnomAD3 exomes AF: 0.00000400 AC: 1 AN: 249902 Hom.: 0 AF XY: 0.00000740 AC XY: 1 AN XY: 135152

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.00

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad SAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00000890

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.0000178 AC: 26 AN: 1461808 Hom.: 0 Cov.: 31 AF XY: 0.0000179 AC XY: 13 AN XY: 727210

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.0000116

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.0000225

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 31

Alfa AF: 0.0000413 Hom.: 0

Bravo AF: 0.00000378

EpiCase AF: 0.0000545

EpiControl AF: 0.00

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:1 Other:1

Revision: criteria provided, single submitter

Submissions by phenotype

not provided Pathogenic:1

Sep 03, 2024

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change affects a donor splice site in intron 6 of the USB1 gene. While this variant is not anticipated to result in nonsense mediated decay, it likely alters RNA splicing and results in a disrupted protein product. This variant is present in population databases (no rsID available, gnomAD 0.0009%). Disruption of this splice site has been observed in individual(s) with poikiloderma with neutropenia (PMID: 21271650). In at least one individual the data is consistent with being in trans (on the opposite chromosome) from a pathogenic variant. It has also been observed to segregate with disease in related individuals. ClinVar contains an entry for this variant (Variation ID: 496749). Variants that disrupt the consensus splice site are a relatively common cause of aberrant splicing (PMID: 17576681, 9536098). Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant may disrupt the consensus splice site. This variant disrupts a region of the USB1 protein in which other variant(s) (p.Cys253Arg) have been observed in individuals with USB1-related conditions (PMID: 31522452). This suggests that this is a clinically significant region of the protein, and that variants that disrupt it are likely to be disease-causing. For these reasons, this variant has been classified as Pathogenic. -

Poikiloderma with neutropenia Other:1

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GeneReviews

Significance: not provided

Review Status: no classification provided

Collection Method: literature only

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.62	D
BayesDel_noAF	Pathogenic	0.15
CADD	Pathogenic	33
DANN	Uncertain	0.99
Eigen	Pathogenic	1.0
Eigen_PC	Pathogenic	0.86
FATHMM_MKL	Uncertain	0.89	D
GERP RS		4.2

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	0.95
SpliceAI score (max)		0.97		Details are displayed if max score is > 0.2
DS_DL_spliceai		0.97		Position offset: -1

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

Publications

LitVar

Other links and lift over

dbSNP: rs1292827495; hg19: chr16-58052960;