1-94019691-C-G

Variant names:

• chr1-94019691-C-G
• rs61750564
• NM_000350.3:c.5087G>C

Variant summary

Our verdict is Pathogenic. The variant received 10 ACMG points: 10P and 0B. PM1 PM2 PM5 PP2 PP3 PP5_Moderate

The NM_000350.3(ABCA4):​c.5087G>C​(p.Ser1696Thr) variant causes a missense change involving the alteration of a conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. 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. S1696R) has been classified as Likely pathogenic.

• Frequency: Genomes: not found (cov: 31)
• Consequence: ABCA4 NM_000350.3 missense
• Clinical Significance: Likely pathogenic criteria provided, single submitter P:1
• Conservation: PhyloP100: 7.85
• Publications: 0 publications found

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 Gene-Disease associations (from GenCC):

• ABCA4-related retinopathy

  Inheritance: AR Classification: DEFINITIVE Submitted by: ClinGen
• cone-rod dystrophy 3

  Inheritance: AR Classification: DEFINITIVE, STRONG Submitted by: Labcorp Genetics (formerly Invitae), G2P, Ambry Genetics
• severe early-childhood-onset retinal dystrophy

  Inheritance: AR Classification: DEFINITIVE, STRONG Submitted by: Laboratory for Molecular Medicine, Labcorp Genetics (formerly Invitae), Ambry Genetics
• retinitis pigmentosa 19

  Inheritance: AR Classification: STRONG Submitted by: Labcorp Genetics (formerly Invitae)
• cone-rod dystrophy

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
• retinitis pigmentosa

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
• Stargardt disease

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet

ACMG classification

Our verdict: Pathogenic. The variant received 10 ACMG points.

• PM1: In a hotspot region, there are 9 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 0 benign, 5 uncertain in NM_000350.3
• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chr1-94019690-G-C is described in ClinVar as Likely_pathogenic. ClinVar VariationId is 438099.Status of the report is no_assertion_criteria_provided, 0 stars.
• PP2: Missense variant in the gene, where a lot of missense mutations are associated with disease in ClinVar. The gene has 578 curated pathogenic missense variants (we use a threshold of 10). The gene has 28 curated benign missense variants. Gene score misZ: -0.65813 (below the threshold of 3.09). Trascript score misZ: 1.3628 (below the threshold of 3.09). GenCC associations: The gene is linked to cone-rod dystrophy 3, retinitis pigmentosa 19, ABCA4-related retinopathy, severe early-childhood-onset retinal dystrophy, cone-rod dystrophy, Stargardt disease, retinitis pigmentosa.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.823
• PP5: Variant 1-94019691-C-G is Pathogenic according to our data. Variant chr1-94019691-C-G is described in ClinVar as Likely_pathogenic. ClinVar VariationId is 2821867.Status of the report is criteria_provided_single_submitter, 1 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
ABCA4	NM_000350.3	c.5087G>C	p.Ser1696Thr	missense_variant	Exon 36 of 50	ENST00000370225.4	NP_000341.2
ABCA4	NM_001425324.1	c.4865G>C	p.Ser1622Thr	missense_variant	Exon 35 of 49		NP_001412253.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
ABCA4	ENST00000370225.4	c.5087G>C	p.Ser1696Thr	missense_variant	Exon 36 of 50	1	NM_000350.3	ENSP00000359245.3
ABCA4	ENST00000460514.1	n.581G>C		non_coding_transcript_exon_variant	Exon 7 of 7	5
ABCA4	ENST00000470771.1	n.197G>C		non_coding_transcript_exon_variant	Exon 2 of 2	3

Frequencies

GnomAD3 genomes Cov.: 31

GnomAD4 exome Cov.: 31

GnomAD4 genome Cov.: 31

ClinVar

Significance: Likely pathogenic

Submissions summary: Pathogenic:1

Revision: criteria provided, single submitter

Submissions by phenotype

not provided Pathogenic:1

Dec 18, 2022

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This variant disrupts the p.Ser1696 amino acid residue in ABCA4. Other variant(s) that disrupt this residue have been determined to be pathogenic (PMID: 18854780, 20128570, 24409374, 29854428). This suggests that this residue is clinically significant, and that variants that disrupt this residue are likely to be disease-causing. 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. 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 not present in population databases (gnomAD no frequency). This sequence change replaces serine, which is neutral and polar, with threonine, which is neutral and polar, at codon 1696 of the ABCA4 protein (p.Ser1696Thr). -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Uncertain	0.35
BayesDel_addAF	Pathogenic	0.17	D
BayesDel_noAF	Uncertain	0.010
CADD	Uncertain	25
DANN	Uncertain	1.0
DEOGEN2	Uncertain	0.70	D;D
Eigen	Pathogenic	0.86
Eigen_PC	Pathogenic	0.84
FATHMM_MKL	Pathogenic	0.98	D
LIST_S2	Pathogenic	0.99	D;D
M_CAP	Pathogenic	0.65	D
MetaRNN	Pathogenic	0.82	D;D
MetaSVM	Uncertain	0.39	D
MutationAssessor	Uncertain	2.9	.;M
PhyloP100		7.8
PrimateAI	Uncertain	0.71	T
PROVEAN	Uncertain	-2.8	.;D
REVEL	Pathogenic	0.65
Sift	Uncertain	0.011	.;D
Sift4G	Uncertain	0.0020	D;D
Polyphen		0.99	.;D
Vest4		0.70
MutPred		0.67		.;Loss of catalytic residue at S1696 (P = 0.2918);
MVP		0.96
MPC		0.39
ClinPred		0.99	D
GERP RS		5.4
Varity_R		0.82
gMVP		0.85
Mutation Taster		=25/75	disease causing

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.020		Details are displayed if max score is > 0.2

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

Other links and lift over

dbSNP: rs61750564; hg19: chr1-94485247;