1-149923867-C-CG

Position:

• chr1-149923867-C-CG

Variant summary

Our verdict is Uncertain significance. Variant got 0 ACMG points: 4P and 4B. PVS1_Strong BS2

The NM_005850.5(SF3B4):​c.1060_1061insC​(p.Arg354ProfsTer132) variant causes a frameshift change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.0000159 in 1,449,332 control chromosomes in the GnomAD database, with no homozygous occurrence. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars).

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.000016 (0 hom.)
• Consequence: SF3B4 NM_005850.5 frameshift
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications P:2 B:1
• Conservation: PhyloP100: 0.767

Genes affected

SF3B4 (HGNC:10771): (splicing factor 3b subunit 4) This gene encodes one of four subunits of the splicing factor 3B. The protein encoded by this gene cross-links to a region in the pre-mRNA immediately upstream of the branchpoint sequence in pre-mRNA in the prespliceosomal complex A. It also may be involved in the assembly of the B, C and E spliceosomal complexes. In addition to RNA-binding activity, this protein interacts directly and highly specifically with subunit 2 of the splicing factor 3B. This protein contains two N-terminal RNA-recognition motifs (RRMs), consistent with the observation that it binds directly to pre-mRNA. [provided by RefSeq, Jul 2008]

ACMG classification

Verdict is Uncertain_significance. Variant got 0 ACMG points.

• PVS1: Loss of function variant, product does not undergo nonsense mediated mRNA decay. Variant is located in the 3'-most 50 bp of the penultimate exon, not predicted to undergo nonsense mediated mRNA decay. There are 4 pathogenic variants in the truncated region.
• BS2: High AC in GnomAdExome4 at 23 AD gene.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
SF3B4	NM_005850.5	c.1060_1061insC	p.Arg354ProfsTer132	frameshift_variant	5/6	ENST00000271628.9

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
SF3B4	ENST00000271628.9	c.1060_1061insC	p.Arg354ProfsTer132	frameshift_variant	5/6	1	NM_005850.5	P1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 0.0000159 AC: 23 AN: 1449332 Hom.: 0 Cov.: 32 AF XY: 0.0000153 AC XY: 11 AN XY: 721278

Gnomad4 AFR exome AF: 0.0000616

Gnomad4 AMR exome AF: 0.000193

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.0000118

Gnomad4 FIN exome AF: 0.0000566

Gnomad4 NFE exome AF: 0.00000722

Gnomad4 OTH exome AF: 0.0000167

GnomAD4 genome Cov.: 32

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Pathogenic:2 Benign:1

Revision: criteria provided, conflicting classifications

Submissions by phenotype

Nager syndrome Pathogenic:1

Pathogenic, no assertion criteria provided

research

Clinical Genetics Research Group, University of Calgary

Sep 07, 2012

- -

not provided Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Aug 03, 2023

For these reasons, this variant has been classified as Pathogenic. ClinVar contains an entry for this variant (Variation ID: 208831). This frameshift has been observed in individual(s) with Nager syndrome (PMID: 22541558, 24003905, 27622494). In at least one individual the variant was observed to be de novo. The frequency data for this variant in the population databases is considered unreliable, as metrics indicate poor data quality at this position in the gnomAD database. This sequence change results in a frameshift in the SF3B4 gene (p.Arg354Profs*132). While this is not anticipated to result in nonsense mediated decay, it is expected to disrupt the last 71 amino acid(s) of the SF3B4 protein and extend the protein by 60 additional amino acid residues. -

not specified Benign:1

Benign, criteria provided, single submitter

clinical testing

Mendelics

May 04, 2022

- -

Computational scores

Source: dbNSFP v4.3

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

Publications

LitVar

Other links and lift over

dbSNP: rs782357237; hg19: chr1-149895759;