chr8-86604091-AC-A

Position:

• chr8-86604091-AC-A

Variant summary

Our verdict is Pathogenic. Variant got 18 ACMG points: 18P and 0B. PVS1 PM2 PP5_Very_Strong

The NM_019098.5(CNGB3):​c.1781+1del variant causes a splice donor change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.0000035 in 1,428,696 control chromosomes in the GnomAD database, with no homozygous occurrence. 1/1 splice prediction tools predicting alterations to normal splicing. Variant has been reported in ClinVar as Likely pathogenic (★★).

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000035 (0 hom.)
• Consequence: CNGB3 NM_019098.5 splice_donor
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:4
• Conservation: PhyloP100: 7.71

Genes affected

CNGB3 (HGNC:2153): (cyclic nucleotide gated channel subunit beta 3) This gene encodes the beta subunit of a cyclic nucleotide-gated ion channel. The encoded beta subunit appears to play a role in modulation of channel function in cone photoreceptors. This heterotetrameric channel is necessary for sensory transduction, and mutations in this gene have been associated with achromatopsia 3, progressive cone dystrophy, and juvenile macular degeneration, also known as Stargardt Disease. [provided by RefSeq, Feb 2010]

ACMG classification

Verdict is Pathogenic. Variant got 18 ACMG points.

• PVS1: Splicing +-2 bp (donor or acceptor) variant, LoF is a know mechanism of disease, No cryptic splice site detected. Exon removal results in frameshift change.
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 8-86604091-AC-A is Pathogenic according to our data. Variant chr8-86604091-AC-A is described in ClinVar as [Likely_pathogenic]. Clinvar id is 427707.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars. Variant chr8-86604091-AC-A is described in Lovd as [Pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
CNGB3	NM_019098.5	c.1781+1del		splice_donor_variant		ENST00000320005.6	NP_061971.3
CNGB3	XM_011517138.3	c.1367+1del		splice_donor_variant			XP_011515440.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
CNGB3	ENST00000320005.6	c.1781+1del		splice_donor_variant		1	NM_019098.5	ENSP00000316605	P1
CNGB3	ENST00000681746.1	c.*192+1del		splice_donor_variant, NMD_transcript_variant				ENSP00000505959
CNGB3	ENST00000681546.1	n.1601+1del		splice_donor_variant, non_coding_transcript_variant

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 0.00000350 AC: 5 AN: 1428696 Hom.: 0 Cov.: 27 AF XY: 0.00000280 AC XY: 2 AN XY: 713162

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: 0.00000370

Gnomad4 OTH exome AF: 0.0000169

GnomAD4 genome Cov.: 32

EpiCase AF: 0.0000545

EpiControl AF: 0.00

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:4

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Achromatopsia 3 Pathogenic:2

Likely pathogenic, criteria provided, single submitter	clinical testing	Counsyl	Mar 24, 2017	- -
Pathogenic, no assertion criteria provided	research	Molecular Genetics Laboratory, Institute for Ophthalmic Research	Mar 27, 2017	- -

Achromatopsia Pathogenic:1

Pathogenic, no assertion criteria provided

clinical testing

Natera, Inc.

Oct 23, 2020

- -

not provided Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Jul 24, 2020

This sequence change affects a donor splice site in intron 15 of the CNGB3 gene. It is expected to disrupt RNA splicing and likely results in an absent or disrupted protein product. This variant is not present in population databases (ExAC no frequency). This variant has been observed in individual(s) with achromatopsia (PMID: 28795510). In at least one individual the data is consistent with the variant being in trans (on the opposite chromosome) from a pathogenic variant. ClinVar contains an entry for this variant (Variation ID: 427707). Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant may disrupt the consensus splice site, but this prediction has not been confirmed by published transcriptional studies. Donor and acceptor splice site variants typically lead to a loss of protein function (PMID: 16199547), and loss-of-function variants in CNGB3 are known to be pathogenic (PMID: 28795510). For these reasons, this variant has been classified as Pathogenic. -

Computational scores

Source: dbNSFP v4.3

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.72		Details are displayed if max score is > 0.2
DS_DL_spliceai		0.72		Position offset: 2

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

Publications

LitVar

Other links and lift over

dbSNP: rs1554607546; hg19: chr8-87616319;