4-47936491-G-T

Variant summary

Our verdict is Uncertain significance. Variant got 1 ACMG points: 2P and 1B. PM2 BP4

The NM_001379270.1(CNGA1):c.1991C>A(p.Pro664Gln) variant causes a missense change. The variant allele was found at a frequency of 0.00000137 in 1,461,878 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. P664L) has been classified as Uncertain significance.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000014 (0 hom.)
• Consequence: CNGA1 NM_001379270.1 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 4.09

Genes affected

CNGA1 (HGNC:2148): (cyclic nucleotide gated channel subunit alpha 1) The protein encoded by this gene is involved in phototransduction. Along with another protein, the encoded protein forms a cGMP-gated cation channel in the plasma membrane, allowing depolarization of rod photoreceptors. This represents the last step in the phototransduction pathway. Defects in this gene are a cause of retinitis pigmentosa autosomal recessive (ARRP) disease. Multiple transcript variants have been found for this gene. [provided by RefSeq, Oct 2019]

LOC101927157 (HGNC:):

NIPAL1 (HGNC:27194): (NIPA like domain containing 1) Predicted to enable magnesium ion transmembrane transporter activity. Predicted to be involved in magnesium ion transport. Predicted to be integral component of membrane. Predicted to be active in membrane. [provided by Alliance of Genome Resources, Apr 2022]

ACMG classification

Verdict is Uncertain_significance. Variant got 1 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (MetaRNN=0.27080745).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
CNGA1	NM_001379270.1	c.1991C>A	p.Pro664Gln	missense_variant	11/11	ENST00000514170.7
LOC101927157	NR_125879.1	n.478+21787G>T		intron_variant, non_coding_transcript_variant

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
CNGA1	ENST00000514170.7	c.1991C>A	p.Pro664Gln	missense_variant	11/11	5	NM_001379270.1	P1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD3 exomes AF: 0.00000802 AC: 2 AN: 249234 Hom.: 0 AF XY: 0.00000740 AC XY: 1 AN XY: 135194

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.00

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: 0.0000177

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000137 AC: 2 AN: 1461878 Hom.: 0 Cov.: 31 AF XY: 0.00000138 AC XY: 1 AN XY: 727240

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: 0.0000187

Gnomad4 NFE exome AF: 8.99e-7

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 32

ExAC AF: 0.00000828 AC: 1

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

not provided Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Invitae

Mar 05, 2020

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. Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant may create or strengthen a splice site, but this prediction has not been confirmed by published transcriptional studies. Algorithms developed to predict the effect of missense changes on protein structure and function are either unavailable or do not agree on the potential impact of this missense change (SIFT: "Tolerated"; PolyPhen-2: "Probably Damaging"; Align-GVGD: "Class C0"). This variant has not been reported in the literature in individuals with CNGA1-related conditions. This variant is present in population databases (rs757837096, ExAC 0.001%). This sequence change replaces proline with glutamine at codon 668 of the CNGA1 protein (p.Pro668Gln). The proline residue is highly conserved and there is a moderate physicochemical difference between proline and glutamine. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.25
BayesDel_addAF	Pathogenic	0.29	D
BayesDel_noAF	Pathogenic	0.19
Cadd	Benign	18
Dann	Uncertain	0.99
Eigen	Benign	-0.18
Eigen_PC	Benign	-0.010
FATHMM_MKL	Pathogenic	0.99	D
M_CAP	Uncertain	0.14	D
MetaRNN	Benign	0.27	T;T;T;T;T
MetaSVM	Uncertain	0.42	D
MutationTaster	Benign	1.0	D;D;D;D;D
PrimateAI	Benign	0.46	T
PROVEAN	Benign	-0.070	N;N;.;N;N
REVEL	Uncertain	0.54
Sift	Benign	0.067	T;T;.;T;T
Sift4G	Benign	0.18	T;T;T;T;T
Polyphen		0.085	.;B;.;B;B
Vest4		0.61
MutPred		0.27		.;Gain of MoRF binding (P = 0.0419);.;Gain of MoRF binding (P = 0.0419);Gain of MoRF binding (P = 0.0419);
MVP		0.94
MPC		0.50
ClinPred		0.81	D
GERP RS		4.5
Varity_R		0.16
gMVP		0.13

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.0		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: rs757837096; hg19: chr4-47938508;