NM_000350.3:c.203C>G

Variant names:

• chr1-94111537-G-C
• rs62654397
• NM_000350.3:c.203C>G

Variant summary

Our verdict is Pathogenic. Variant got 16 ACMG points: 16P and 0B. PM1 PM5 PP3_Strong PP5_Very_Strong

The NM_000350.3(ABCA4):​c.203C>G​(p.Pro68Arg) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.0000041 in 1,461,852 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. P68L) has been classified as Likely pathogenic.

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 0.0000041 (0 hom.)
• Consequence: ABCA4 NM_000350.3 missense
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:4 O:1
• Conservation: PhyloP100: 9.79

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]

ACMG classification

Verdict is Pathogenic. Variant got 16 ACMG points.

• PM1: In a hotspot region, there are 8 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 1 benign, 3 uncertain in NM_000350.3
• PM5: Other missense variant is known to change same aminoacid residue: Variant chr1-94111537-G-A is described in ClinVar as [Likely_pathogenic]. Clinvar id is 99113.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.987
• PP5: Variant 1-94111537-G-C is Pathogenic according to our data. Variant chr1-94111537-G-C is described in ClinVar as [Likely_pathogenic]. Clinvar id is 99112.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars. Variant chr1-94111537-G-C is described in Lovd as [Likely_pathogenic]. Variant chr1-94111537-G-C is described in Lovd as [Likely_pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
ABCA4	NM_000350.3	c.203C>G	p.Pro68Arg	missense_variant	Exon 3 of 50	ENST00000370225.4	NP_000341.2
ABCA4	NM_001425324.1	c.203C>G	p.Pro68Arg	missense_variant	Exon 3 of 49		NP_001412253.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
ABCA4	ENST00000370225.4	c.203C>G	p.Pro68Arg	missense_variant	Exon 3 of 50	1	NM_000350.3	ENSP00000359245.3
ABCA4	ENST00000649773.1	c.203C>G	p.Pro68Arg	missense_variant	Exon 3 of 19			ENSP00000496882.1

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome AF: 0.00000410 AC: 6 AN: 1461852 Hom.: 0 Cov.: 34 AF XY: 0.00000138 AC XY: 1 AN XY: 727230

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: 0.00000540

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 33

Alfa AF: 0.0000688 Hom.: 0

Bravo AF: 0.0000113

EpiCase AF: 0.0000545

EpiControl AF: 0.00

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:4 Other:1

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Retinal dystrophy Pathogenic:2

May 27, 2019

Blueprint Genetics

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Jan 01, 2010

Institute of Human Genetics, Univ. Regensburg, Univ. Regensburg

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

not provided Pathogenic:1 Other:1

-

Retina International

Significance: not provided

Review Status: no classification provided

Collection Method: literature only

- -

Aug 08, 2024

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change replaces proline, which is neutral and non-polar, with arginine, which is basic and polar, at codon 68 of the ABCA4 protein (p.Pro68Arg). This variant is present in population databases (rs62654397, gnomAD 0.007%). This missense change has been observed in individual(s) with Stargardt disease (PMID: 11726554, 22247458, 28118664). In at least one individual the data is consistent with being in trans (on the opposite chromosome) from a pathogenic variant. It has also been observed to segregate with disease in related individuals. ClinVar contains an entry for this variant (Variation ID: 99112). 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 with a positive predictive value of 95%. For these reasons, this variant has been classified as Pathogenic. -

ABCA4-related disorder Pathogenic:1

Oct 02, 2017

Illumina Laboratory Services, Illumina

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

TheABCA4 c.203C>G (p.Pro68Arg) missense variant has been reported in three studies in which it is identified in four individuals, including a sibling pair, with recessively inherited Stargardt disease, all in a compound heterozygous state with a second missense variant (Shroyer et al. 2000; Cideciyan et al. 2012; Schulz et al. 2017). The mother of the affected siblings was diagnosed with age-related macular degeneration and carried the p.Pro68Arg variant in a heterozygous state (Shroyer et al. 2000). The variant was absent from 440 control chromosomes (Lewis et al. 1999) and is reported at a frequency of 0.00007 in the European (non-Finnish) population of the Genome Aggregation Database, but this is based on one allele so the variant is presumed to be rare. Another missense variant at the same amino acid position (p.Pro68Leu) has also been seen in individuals with ABCA4-related conditions, including at least one individual with Stargardt disease who carried the variant in a compound heterozygous state (Rivera et al. 2000). Based on the collective evidence, the p.Pro68Arg variant is classified as likely pathogenic for ABCA4-related disorders. This variant was observed by ICSL as part of a predisposition screen in an ostensibly healthy population. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.68
BayesDel_addAF	Pathogenic	0.56	D
BayesDel_noAF	Pathogenic	0.57
CADD	Uncertain	25
DANN	Uncertain	1.0
DEOGEN2	Pathogenic	0.81	D;.
Eigen	Pathogenic	0.94
Eigen_PC	Pathogenic	0.91
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Uncertain	0.93	D;D
M_CAP	Pathogenic	0.60	D
MetaRNN	Pathogenic	0.99	D;D
MetaSVM	Pathogenic	0.95	D
MutationAssessor	Pathogenic	3.0	M;.
PrimateAI	Uncertain	0.75	T
PROVEAN	Pathogenic	-6.1	D;.
REVEL	Pathogenic	0.92
Sift	Benign	0.061	T;.
Sift4G	Uncertain	0.055	T;.
Polyphen		1.0	D;.
Vest4		0.97
MutPred		0.93		Loss of catalytic residue at W69 (P = 0.0171);Loss of catalytic residue at W69 (P = 0.0171);
MVP		1.0
MPC		0.48
ClinPred		1.0	D
GERP RS		5.6
Varity_R		0.49
gMVP		0.96

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: rs62654397; hg19: chr1-94577093;