chr8-86670990-C-CA

Variant names:

• chr8-86670990-C-CA
• rs748993388
• NM_019098.5:c.446_447insT

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.446_447insT​(p.Lys149AsnfsTer30) variant causes a frameshift change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000205 in 1,460,962 control chromosomes in the GnomAD database, with no homozygous occurrence. Variant has been reported in ClinVar as Likely pathogenic (★★). Synonymous variant affecting the same amino acid position (i.e. K149K) has been classified as Likely benign. Variant results in nonsense mediated mRNA decay.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000021 (0 hom.)
• Consequence: CNGB3 NM_019098.5 frameshift
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:3
• Conservation: PhyloP100: 3.15

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: Loss of function variant, product undergoes nonsense mediated mRNA decay. LoF is a known mechanism of disease.
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 8-86670990-C-CA is Pathogenic according to our data. Variant chr8-86670990-C-CA is described in ClinVar as [Likely_pathogenic]. Clinvar id is 370100.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
CNGB3	NM_019098.5	c.446_447insT	p.Lys149AsnfsTer30	frameshift_variant	Exon 4 of 18	ENST00000320005.6	NP_061971.3
CNGB3	XM_011517138.3	c.32_33insT	p.Lys11AsnfsTer30	frameshift_variant	Exon 2 of 16		XP_011515440.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
CNGB3	ENST00000320005.6	c.446_447insT	p.Lys149AsnfsTer30	frameshift_variant	Exon 4 of 18	1	NM_019098.5	ENSP00000316605.5
CNGB3	ENST00000680314.1	n.207_208insT		non_coding_transcript_exon_variant	Exon 2 of 3
CNGB3	ENST00000681746.1	n.446_447insT		non_coding_transcript_exon_variant	Exon 4 of 19			ENSP00000505959.1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD3 exomes AF: 0.00000398 AC: 1 AN: 251468 Hom.: 0 AF XY: 0.00000736 AC XY: 1 AN XY: 135904

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.0000289

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: 0.00

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000205 AC: 3 AN: 1460962 Hom.: 0 Cov.: 32 AF XY: 0.00000138 AC XY: 1 AN XY: 726778

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.0000224

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: 0.00

Gnomad4 OTH exome AF: 0.0000332

GnomAD4 genome Cov.: 32

Bravo AF: 0.00000756

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:3

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Achromatopsia 3 Pathogenic:2

Nov 20, 2015

Counsyl

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

May 22, 2022

3billion

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The variant is observed at an extremely low frequency in the gnomAD v2.1.1 dataset (total allele frequency: <0.001%). Frameshift: predicted to result in a loss or disruption of normal protein function through nonsense-mediated decay (NMD) or protein truncation. Multiple pathogenic variants are reported downstream of the variant. The variant has been reported at least twice as pathogenic without evidence for the classification (ClinVar ID: VCV000370100). Therefore, this variant is classified as pathogenic according to the recommendation of ACMG/AMP guideline. -

not provided Pathogenic:1

Oct 10, 2024

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change creates a premature translational stop signal (p.Lys149Asnfs*30) in the CNGB3 gene. It is expected to result in an absent or disrupted protein product. Loss-of-function variants in CNGB3 are known to be pathogenic (PMID: 28795510). This variant is present in population databases (rs748993388, gnomAD 0.003%). This premature translational stop signal has been observed in individual(s) with achromatopsia (PMID: 12357335). This variant is also known as c.492_493insT. ClinVar contains an entry for this variant (Variation ID: 370100). 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)		0.010		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: rs748993388; hg19: chr8-87683218;