1-93997943-G-T

Position:

• chr1-93997943-G-T

Variant summary

Our verdict is Likely pathogenic. Variant got 8 ACMG points: 8P and 0B. PM2 PM5 PP3_Moderate PP5_Moderate

The NM_000350.3(ABCA4):​c.6647C>A​(p.Ala2216Glu) variant causes a missense change. The variant allele was found at a frequency of 0.00000205 in 1,461,838 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. A2216V) has been classified as Likely pathogenic.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000021 (0 hom.)
• Consequence: ABCA4 NM_000350.3 missense
• Clinical Significance: Likely pathogenic criteria provided, single submitter P:1
• Conservation: PhyloP100: 6.77

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 Likely_pathogenic. Variant got 8 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chr1-93997943-G-A is described in ClinVar as [Conflicting_classifications_of_pathogenicity]. Clinvar id is 236149.We mark this variant Likely_pathogenic, oryginal submissions are: {Uncertain_significance=1, Pathogenic=3}.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.865
• PP5: Variant 1-93997943-G-T is Pathogenic according to our data. Variant chr1-93997943-G-T is described in ClinVar as [Likely_pathogenic]. Clinvar id is 2856450.Status of the report is criteria_provided_single_submitter, 1 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
ABCA4	NM_000350.3	c.6647C>A	p.Ala2216Glu	missense_variant	48/50	ENST00000370225.4	NP_000341.2
ABCA4	XM_047416704.1	c.6425C>A	p.Ala2142Glu	missense_variant	47/49

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
ABCA4	ENST00000370225.4	c.6647C>A	p.Ala2216Glu	missense_variant	48/50	1	NM_000350.3	ENSP00000359245.3

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD3 exomes AF: 0.00000398 AC: 1 AN: 251402 Hom.: 0 AF XY: 0.00 AC XY: 0 AN XY: 135876

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: 1461838 Hom.: 0 Cov.: 31 AF XY: 0.00000138 AC XY: 1 AN XY: 727214

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: 0.00000180

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 32

ClinVar

Significance: Likely pathogenic

Submissions summary: Pathogenic:1

Revision: criteria provided, single submitter

Submissions by phenotype

not provided Pathogenic:1

Likely pathogenic, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Aug 24, 2023

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. This variant disrupts the p.Ala2216 amino acid residue in ABCA4. Other variant(s) that disrupt this residue have been determined to be pathogenic (PMID: 10958763, 28118664, 29925512, 32619608). This suggests that this residue is clinically significant, and that variants that disrupt this residue are likely to be disease-causing. 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. This variant has not been reported in the literature in individuals affected with ABCA4-related conditions. This variant is present in population databases (no rsID available, gnomAD 0.003%). This sequence change replaces alanine, which is neutral and non-polar, with glutamic acid, which is acidic and polar, at codon 2216 of the ABCA4 protein (p.Ala2216Glu). -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.74
BayesDel_addAF	Pathogenic	0.22	D
BayesDel_noAF	Pathogenic	0.16
CADD	Pathogenic	27
DANN	Uncertain	0.99
DEOGEN2	Benign	0.36	T;D
Eigen	Pathogenic	0.75
Eigen_PC	Pathogenic	0.68
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Uncertain	0.94	D;D
M_CAP	Uncertain	0.16	D
MetaRNN	Pathogenic	0.86	D;D
MetaSVM	Uncertain	0.042	D
MutationAssessor	Pathogenic	3.9	.;H
PrimateAI	Uncertain	0.66	T
PROVEAN	Uncertain	-3.3	.;D
REVEL	Pathogenic	0.78
Sift	Uncertain	0.018	.;D
Sift4G	Uncertain	0.0020	D;D
Polyphen		1.0	.;D
Vest4		0.87
MutPred		0.61		.;Gain of disorder (P = 0.025);
MVP		0.98
MPC		0.50
ClinPred		0.99	D
GERP RS		4.4
Varity_R		0.58
gMVP		0.77

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: rs886044763; hg19: chr1-94463499;