2-98369938-G-C

Variant summary

Our verdict is Likely pathogenic. Variant got 9 ACMG points: 9P and 0B. PVS1_Moderate PM2 PP3_Strong PP5

The NM_001298.3(CNGA3):c.-37-1G>C variant causes a splice acceptor change. The variant allele was found at a frequency of 0.00000716 in 1,535,868 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 3/3 splice prediction tools predicting alterations to normal splicing. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars).

• Frequency:
  • Genomes: 𝑓 0.0000066 (0 hom., cov: 33)
  • Exomes 𝑓: 0.0000072 (0 hom.)
• Consequence: CNGA3 NM_001298.3 splice_acceptor
• Scores: Splicing: ADA: 1.000
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications P:3 U:1
• Conservation: PhyloP100: 4.91

Genes affected

CNGA3 (HGNC:2150): (cyclic nucleotide gated channel subunit alpha 3) This gene encodes a member of the cyclic nucleotide-gated cation channel protein family which is required for normal vision and olfactory signal transduction. Mutations in this gene are associated with achromatopsia (rod monochromacy) and color blindness. Two alternatively spliced transcripts encoding different isoforms have been described. [provided by RefSeq, Jul 2008]

ACMG classification

Verdict is Likely_pathogenic. Variant got 9 ACMG points.

• PVS1: Splicing variant, NOT destroyed by nmd, known LOF gene, truncates exone, which is 0.06570744 fraction of the gene. No cryptic splice site detected. Exon removal is inframe change.
• PM2: Very rare variant in population databases, with high coverage
• PP3: Splicing scoreres supports a deletorius effect: Scorers claiming Pathogenic: dbscSNV1_ADA, dbscSNV1_RF, max_spliceai. No scorers claiming Uncertain. No scorers claiming Benign.
• PP5: Variant 2-98369938-G-C is Pathogenic according to our data. Variant chr2-98369938-G-C is described in ClinVar as [Conflicting_classifications_of_pathogenicity]. Clinvar id is 503559.We mark this variant Likely_pathogenic, oryginal submissions are: {Uncertain_significance=1, Likely_pathogenic=1}. Variant chr2-98369938-G-C is described in Lovd as [Pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
CNGA3	NM_001298.3	c.-37-1G>C		splice_acceptor_variant		ENST00000272602.7

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
CNGA3	ENST00000272602.7	c.-37-1G>C		splice_acceptor_variant		1	NM_001298.3	A1
CNGA3	ENST00000436404.6	c.-37-1G>C		splice_acceptor_variant		1		P4

Frequencies

GnomAD3 genomes AF: 0.00000657 AC: 1 AN: 152122 Hom.: 0 Cov.: 33

Gnomad AFR AF: 0.00

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.00

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.00

Gnomad SAS AF: 0.000207

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.00

Gnomad OTH AF: 0.00

GnomAD4 exome AF: 0.00000723 AC: 10 AN: 1383746 Hom.: 0 Cov.: 23 AF XY: 0.00000722 AC XY: 5 AN XY: 692256

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: 0.0000119

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 9.58e-7

Gnomad4 OTH exome AF: 0.000121

GnomAD4 genome AF: 0.00000657 AC: 1 AN: 152122 Hom.: 0 Cov.: 33 AF XY: 0.00 AC XY: 0 AN XY: 74298

Gnomad4 AFR AF: 0.00

Gnomad4 AMR AF: 0.00

Gnomad4 ASJ AF: 0.00

Gnomad4 EAS AF: 0.00

Gnomad4 SAS AF: 0.000207

Gnomad4 FIN AF: 0.00

Gnomad4 NFE AF: 0.00

Gnomad4 OTH AF: 0.00

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Pathogenic:3 Uncertain:1

Revision: criteria provided, conflicting classifications

Submissions by phenotype

not provided Pathogenic:2 Uncertain:1

Uncertain significance, criteria provided, single submitter	clinical testing	Invitae	Oct 12, 2021	This sequence change falls in intron 1 of the CNGA3 gene. It does not directly change the encoded amino acid sequence of the CNGA3 protein. RNA analysis indicates that this variant induces altered splicing and is likely to result in the loss of the initiator methionine. This variant is not present in population databases (ExAC no frequency). This variant has been observed in individual(s) with macular dystrophy (PMID: 30418171). ClinVar contains an entry for this variant (Variation ID: 503559). Variants that disrupt the consensus splice site are a relatively common cause of aberrant splicing (PMID: 17576681, 9536098). Studies have shown that this variant results in skipping of part of exon 2, and is expected to result in the loss of the initiator methionine (PMID: 30418171). 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. -
Likely pathogenic, no assertion criteria provided	clinical testing	Clinical Genetics, Academic Medical Center	-	- -
Pathogenic, no assertion criteria provided	clinical testing	Joint Genome Diagnostic Labs from Nijmegen and Maastricht, Radboudumc and MUMC+	-	- -

Achromatopsia Pathogenic:1

Likely pathogenic, criteria provided, single submitter

research

Molecular Genetics Laboratory, Institute for Ophthalmic Research

Mar 20, 2018

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.40
Cadd	Pathogenic	28
Dann	Uncertain	0.98

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	0.96
SpliceAI score (max)		0.96		Details are displayed if max score is > 0.2
DS_AL_spliceai		0.96		Position offset: 1

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

Publications

LitVar

Other links and lift over

dbSNP: rs1553447991; hg19: chr2-98986401;