20-17494135-A-TT

Position:

• chr20-17494135-A-TT

Variant summary

Our verdict is Uncertain significance. Variant got 4 ACMG points: 4P and 0B. PVS1_Moderate PM2

The NM_001195.5(BFSP1):​c.1937delinsAA​(p.Val646GlufsTer29) variant causes a frameshift change involving the alteration of a conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. Variant has been reported in ClinVar as Uncertain significance (★).

• Frequency: Genomes: not found (cov: 33)
• Consequence: BFSP1 NM_001195.5 frameshift
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 8.56

Genes affected

BFSP1 (HGNC:1040): (beaded filament structural protein 1) This gene encodes a lens-specific intermediate filament-like protein named filensin. The encoded protein is expressed in lens fiber cells after differentiation has begun. This protein functions as a component of the beaded filament which is a cytoskeletal structure found in lens fiber cells. Mutations in this gene are the cause of autosomal recessive cortical juvenile-onset cataract. Alternate splicing results in multiple transcript variants. [provided by RefSeq, Jul 2013]

ACMG classification

Verdict is Uncertain_significance. Variant got 4 ACMG points.

• PVS1: Loss of function variant, product does not undergo nonsense mediated mRNA decay. Variant is located in the 3'-most exon, not predicted to undergo nonsense mediated mRNA decay. Fraction of 0.0305 CDS is truncated, and there are 0 pathogenic variants in the truncated region.
• PM2: Very rare variant in population databases, with high coverage

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
BFSP1	NM_001195.5	c.1937delinsAA	p.Val646GlufsTer29	frameshift_variant	8/8	ENST00000377873.8	NP_001186.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
BFSP1	ENST00000377873.8	c.1937delinsAA	p.Val646GlufsTer29	frameshift_variant	8/8	1	NM_001195.5	ENSP00000367104	P1
BFSP1	ENST00000377868.6	c.1562delinsAA	p.Val521GlufsTer29	frameshift_variant	8/8	1		ENSP00000367099
BFSP1	ENST00000536626.7	c.1520delinsAA	p.Val507GlufsTer29	frameshift_variant	9/9	2		ENSP00000442522

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome Cov.: 31

GnomAD4 genome Cov.: 33

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Cataract 33 Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Sep 18, 2017

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. Experimental studies and prediction algorithms are not available for this variant, and the functional significance of the disrupted amino acids is currently unknown. This variant has not been reported in the literature in individuals with BFSP1-related disease. This variant is not present in population databases (ExAC no frequency). This sequence change results in a premature translational stop signal in the BFSP1 gene (p.Glu647Glyfs*28). While this is not anticipated to result in nonsense mediated decay, it is expected to disrupt the last 20 amino acids of the BFSP1 protein. -

Computational scores

Source: dbNSFP v4.3

Splicing

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

Publications

LitVar

Other links and lift over

dbSNP: rs1555799947; hg19: chr20-17474780;