3-133400332-C-CT

Position:

• chr3-133400332-C-CT

Variant summary

Our verdict is Likely pathogenic. Variant got 8 ACMG points: 8P and 0B. PVS1

The NM_003571.4(BFSP2):​c.251dup​(p.Leu85ProfsTer25) variant causes a frameshift change. The variant allele was found at a frequency of 0.00000958 in 1,461,698 control chromosomes in the GnomAD database, with no homozygous occurrence. Variant has been reported in ClinVar as Uncertain significance (★). Variant results in nonsense mediated mRNA decay.

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 0.0000096 (0 hom.)
• Consequence: BFSP2 NM_003571.4 frameshift
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 7.06

Genes affected

BFSP2 (HGNC:1041): (beaded filament structural protein 2) More than 99% of the vertebrate ocular lens is comprised of terminally differentiated lens fiber cells. Two lens-specific intermediate filament-like proteins, the protein product of this gene (phakinin), and filensin, are expressed only after fiber cell differentiation has begun. Both proteins are found in a structurally unique cytoskeletal element that is referred to as the beaded filament (BF). Mutations in this gene have been associated with juvenile-onset, progressive cataracts and Dowling-Meara epidermolysis bullosa simplex. [provided by RefSeq, Jun 2009]

ACMG classification

Verdict is Likely_pathogenic. Variant got 8 ACMG points.

• PVS1: Loss of function variant, product undergoes nonsense mediated mRNA decay. LoF is a known mechanism of disease.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
BFSP2	NM_003571.4	c.251dup	p.Leu85ProfsTer25	frameshift_variant	1/7	ENST00000302334.3
BFSP2	XM_017007315.2	c.251dup	p.Leu85ProfsTer25	frameshift_variant	1/6

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
BFSP2	ENST00000302334.3	c.251dup	p.Leu85ProfsTer25	frameshift_variant	1/7	1	NM_003571.4	P1
BFSP2	ENST00000513441.1	n.261dup		non_coding_transcript_exon_variant	1/2	5

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome AF: 0.00000958 AC: 14 AN: 1461698 Hom.: 0 Cov.: 31 AF XY: 0.00000963 AC XY: 7 AN XY: 727136

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: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.0000126

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 33

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Cataract 12 multiple types Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Illumina Laboratory Services, Illumina

Apr 28, 2017

The BFSP2 c.251dupT (p.Leu85ProfsTer25) variant results in a frameshift, and is predicted to cause a premature termination of the protein. A literature search was performed for the gene, cDNA change, and amino acid change. No publications were found based on this search. This variant is not found in the 1000 Genomes Project, the Exome Sequencing Project, or the Exome Aggregation Consortium. Based on the variant frequency, disease prevalence, disease penetrance and inheritance mode, this variant could not be ruled out of causing disease. Due to the potential impact of frameshift variants and the lack of clarifying evidence, this variant is classified as a variant of unknown significance but suspicious for pathogenicity for cataracts. This variant was observed by ICSL as part of a predisposition screen in an ostensibly healthy population. -

Computational scores

Source: dbNSFP v4.3

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: rs886058008; hg19: chr3-133119176;