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UniProtKB/Swiss-Prot P78363: Variant p.Arg18Trp

Retinal-specific ATP-binding cassette transporter
Gene: ABCA4
Chromosomal location: 1p21-p22.1
Variant information

Variant position:  18
The position of the amino-acid change on the UniProtKB canonical protein sequence.

Type of variant:  Disease [Disclaimer]
The variants are classified into three categories: Disease, Polymorphism and Unclassified.
  • Disease: Variants implicated in disease according to literature reports.
  • Polymorphism: Variants not reported to be implicated in disease.
  • Unclassified: Variants with uncertain implication in disease according to literature reports. Evidence against or in favor of a pathogenic role is limited and/or conflicting.

Residue change:  From Arginine (R) to Tryptophan (W) at position 18 (R18W, p.Arg18Trp).
Indicates the amino acid change of the variant. The one-letter and three-letter codes for amino acids used in UniProtKB/Swiss-Prot are those adopted by the commission on Biochemical Nomenclature of the IUPAC-IUB.

Physico-chemical properties:  Change from large size and basic (R) to large size and aromatic (W)
The physico-chemical property of the reference and variant residues and the change implicated.

BLOSUM score:  -3
The score within a Blosum matrix for the corresponding wild-type to variant amino acid change. The log-odds score measures the logarithm for the ratio of the likelihood of two amino acids appearing by chance. The Blosum62 substitution matrix is used. This substitution matrix contains scores for all possible exchanges of one amino acid with another:
  • Lowest score: -4 (low probability of substitution).
  • Highest score: 11 (high probability of substitution).
More information can be found on the following page

Involvement in disease:  Stargardt disease 1 (STGD1) [MIM:248200]: A common hereditary macular degeneration. It is characterized by decreased central vision, atrophy of the macula and underlying retinal pigment epithelium, and frequent presence of prominent flecks in the posterior pole of the retina. {ECO:0000269|PubMed:10090887, ECO:0000269|PubMed:10206579, ECO:0000269|PubMed:10612508, ECO:0000269|PubMed:10634594, ECO:0000269|PubMed:10711710, ECO:0000269|PubMed:10746567, ECO:0000269|PubMed:10958763, ECO:0000269|PubMed:11328725, ECO:0000269|PubMed:11385708, ECO:0000269|PubMed:11527935, ECO:0000269|PubMed:11594993, ECO:0000269|PubMed:18977788, ECO:0000269|PubMed:24444108, ECO:0000269|PubMed:9054934, ECO:0000269|PubMed:9490294, ECO:0000269|PubMed:9503029, ECO:0000269|PubMed:9781034, ECO:0000269|PubMed:9973280}. Note=The disease is caused by mutations affecting the gene represented in this entry.
The name and a short description of the disease associated with the variant. For more information about the disease, the user can refer to OMIM, following the link provided after the disease acronym.

Variant description:  In STGD1.
Any additional useful information about the variant.

Other resources:  
Links to websites of interest for the variant.



Sequence information

Variant position:  18
The position of the amino-acid change on the UniProtKB canonical protein sequence.

Protein sequence length:  2273
The length of the canonical sequence.

Location on the sequence:   MGFVRQIQLLLWKNWTL  R KRQKIRFVVELVWPLSLFLV
The residue change on the sequence. Unless the variant is located at the beginning or at the end of the protein sequence, both residues upstream (20) and downstream (20) of the variant will be shown.

Residue conservation: 
The multiple alignment of the region surrounding the variant against various orthologous sequences.

Human                         MGFVRQIQLLLWKNWTLRKRQKIRFVVELVWPLSLFLV

Mouse                         MGFLRQIQLLLWKNWTLRKRQKIRFVVELVWPLSLFLV

Slime mold                    ESIKNQLIPLLKKNWTLKGKSKIKLLLEILLPLISIGI

Sequence annotation in neighborhood:  
The regions or sites of interest surrounding the variant. In general the features listed are posttranslational modifications, binding sites, enzyme active sites, local secondary structure or other characteristics reported in the cited references. The "Sequence annotation in neighborhood" lines have a fixed format:
  • Type: the type of sequence feature.
  • Positions: endpoints of the sequence feature.
  • Description: contains additional information about the feature.

TypePositionsDescription
Chain 1 – 2273 Retinal-specific ATP-binding cassette transporter
Topological domain 1 – 21 Cytoplasmic


Literature citations

Complete exon-intron structure of the retina-specific ATP binding transporter gene (ABCR) allows the identification of novel mutations underlying Stargardt disease.
Gerber S.; Rozet J.-M.; van de Pol T.J.R.; Hoyng C.B.; Munnich A.; Blankenagel A.; Kaplan J.; Cremers F.P.M.;
Genomics 48:139-142(1998)
Cited for: NUCLEOTIDE SEQUENCE [GENOMIC DNA]; VARIANTS STGD1 TRP-18 AND CYS-212; VARIANT ASP-1817;

Spectrum of ABCR gene mutations in autosomal recessive macular dystrophies.
Rozet J.-M.; Gerber S.; Souied E.; Perrault I.; Chatelin S.; Ghazi I.; Leowski C.; Dufier J.-L.; Munnich A.; Kaplan J.;
Eur. J. Hum. Genet. 6:291-295(1998)
Cited for: VARIANTS STGD1 TRP-18; CYS-212; HIS-636; MET-1019; VAL-1038; CYS-1108; TRP-1640; SER-1977 AND HIS-2107; VARIANTS FFM PRO-11; PRO-541; VAL-1038; GLU-1091; CYS-1508; PHE-1970 AND ARG-1971;

Disclaimer: Any medical or genetic information present in this entry is provided for research, educational and informational purposes only. They are not in any way intended to be used as a substitute for professional medical advice, diagnostic, treatment or care.