rs1553188682

Positions:

• chr1-94021892-A-C

Variant summary

Our verdict is Pathogenic. Variant got 10 ACMG points: 10P and 0B. PM1 PM2 PP3_Strong PP5_Moderate

The NM_000350.3(ABCA4):​c.4727T>G​(p.Leu1576Arg) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000137 in 1,461,894 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Likely pathogenic (★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. L1576F) has been classified as Uncertain significance.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000014 (0 hom.)
• Consequence: ABCA4 NM_000350.3 missense
• Clinical Significance: Likely pathogenic criteria provided, single submitter P:2
• Conservation: PhyloP100: 8.35

Genes affected

ABCA4 (HGNC:34): (ATP binding cassette subfamily A member 4) The membrane-associated protein encoded by this gene is a member of the superfamily of ATP-binding cassette (ABC) transporters. ABC proteins transport various molecules across extra- and intracellular membranes. ABC genes are divided into seven distinct subfamilies (ABC1, MDR/TAP, MRP, ALD, OABP, GCN20, White). This protein is a member of the ABC1 subfamily. Members of the ABC1 subfamily comprise the only major ABC subfamily found exclusively in multicellular eukaryotes. This protein is a retina-specific ABC transporter with N-retinylidene-PE as a substrate. It is expressed exclusively in retina photoreceptor cells, and the gene product mediates transport of an essental molecule, all-trans-retinal aldehyde (atRAL), across the photoreceptor cell membrane. Mutations in this gene are found in patients diagnosed with Stargardt disease, a form of juvenile-onset macular degeneration. Mutations in this gene are also associated with retinitis pigmentosa-19, cone-rod dystrophy type 3, early-onset severe retinal dystrophy, fundus flavimaculatus, and macular degeneration age-related 2. [provided by RefSeq, Sep 2019]

ABCA4 (HGNC:):

ACMG classification

Verdict is Pathogenic. Variant got 10 ACMG points.

• PM1: In a hotspot region, there are 3 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 0 benign, 10 uncertain in NM_000350.3
• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.961
• PP5: Variant 1-94021892-A-C is Pathogenic according to our data. Variant chr1-94021892-A-C is described in ClinVar as [Likely_pathogenic]. Clinvar id is 438097.Status of the report is criteria_provided_single_submitter, 1 stars. Variant chr1-94021892-A-C is described in Lovd as [Likely_pathogenic]. Variant chr1-94021892-A-C is described in Lovd as [Likely_pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
ABCA4	NM_000350.3	c.4727T>G	p.Leu1576Arg	missense_variant	33/50	ENST00000370225.4	NP_000341.2
ABCA4	XM_047416704.1	c.4505T>G	p.Leu1502Arg	missense_variant	32/49

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
ABCA4	ENST00000370225.4	c.4727T>G	p.Leu1576Arg	missense_variant	33/50	1	NM_000350.3	ENSP00000359245.3
ABCA4	ENST00000460514.1	n.221T>G		non_coding_transcript_exon_variant	4/7	5

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 0.00000137 AC: 2 AN: 1461894 Hom.: 0 Cov.: 32 AF XY: 0.00 AC XY: 0 AN XY: 727248

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: 0.00000180

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 32

ClinVar

Significance: Likely pathogenic

Submissions summary: Pathogenic:2

Revision: criteria provided, single submitter

Submissions by phenotype

Severe early-childhood-onset retinal dystrophy Pathogenic:1

Likely pathogenic, no assertion criteria provided

research

NIHR Bioresource Rare Diseases, University of Cambridge

Jan 01, 2015

- -

not provided Pathogenic:1

Likely pathogenic, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Aug 10, 2023

This variant is not present in population databases (gnomAD no frequency). This sequence change replaces leucine, which is neutral and non-polar, with arginine, which is basic and polar, at codon 1576 of the ABCA4 protein (p.Leu1576Arg). This missense change has been observed in individual(s) with Stargardt Disease (PMID: 28041643). ClinVar contains an entry for this variant (Variation ID: 438097). Advanced modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) performed at Invitae indicates that this missense variant is expected to disrupt ABCA4 protein function. In summary, the currently available evidence indicates that the variant is pathogenic, but additional data are needed to prove that conclusively. Therefore, this variant has been classified as Likely Pathogenic. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Uncertain	0.40
BayesDel_addAF	Pathogenic	0.32	D
BayesDel_noAF	Pathogenic	0.22
CADD	Benign	22
DANN	Uncertain	0.98
DEOGEN2	Benign	0.36	T;D
Eigen	Uncertain	0.25
Eigen_PC	Uncertain	0.24
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Benign	0.74	T;T
M_CAP	Pathogenic	0.31	D
MetaRNN	Pathogenic	0.96	D;D
MetaSVM	Uncertain	-0.22	T
MutationAssessor	Benign	1.4	.;L
PrimateAI	Uncertain	0.49	T
PROVEAN	Uncertain	-3.4	.;D
REVEL	Uncertain	0.63
Sift	Uncertain	0.0010	.;D
Sift4G	Benign	0.075	T;D
Polyphen		0.83	.;P
Vest4		0.57
MutPred		0.84		.;Gain of methylation at L1576 (P = 0.023);
MVP		0.94
MPC		0.30
ClinPred		0.95	D
GERP RS		6.2
Varity_R		0.78
gMVP		0.86

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.050		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: rs1553188682; hg19: chr1-94487448; COSMIC: COSV64674232; COSMIC: COSV64674232;