Overview

Clinical Phenotype: Alzheimer's Disease
Position: (GRCh38/hg38):Chr11:121621073 G>A
Position: (GRCh37/hg19):Chr11:121491782 G>A
dbSNP ID: rs1792120
Coding/Non-Coding: Coding
DNA Change: Substitution
Expected Protein Consequence: Missense
Codon Change: GTT to ATT
Reference Isoform: SORL1 Isoform 1 (2214 aa)
Genomic Region: Exon 44

Findings

Although G is the reference allele at this site, A is the ancestral allele, and the variant has been reported as both V1967I (GTT to ATT) and I1967V (ATT to GTT). Both alleles have been reported in Alzheimer’s cases and in controls.

Two studies reported that this variant—in these cases, G was designated as the risk allele—was not associated with AD in cohorts identified as Caucasian and European American (Fernández et al., 2016; Sassi et al., 2016).

Seven carriers of the G allele—all Alzheimer’s cases—were reported among 15,808 AD cases and 16,097 controls in a study that combined data from multiple European and American cohorts (Holstege et al., 2022).

In a family- and cohort-based study of Caribbean Hispanics (Vardarajan et al., 2015), joint linkage and association analysis, an analytical method that allows researchers to analyze together data from families and unrelated subjects, showed that the G allele associated with Alzheimer’s disease in this population (Vardarajan et al., 2015).

The V1967I variant is classified as benign by the criteria of Holstege et al. (Holstege et al., 2017).

Functional Consequences

Valine-1697 is located in the fifth of SORL1’s six 3Fn domains—named for fibronectin, the protein in which homologous domains were first described. SORL1’s 3Fn-cassette mediates receptor dimerization, which facilitates retromer-dependent transport of cargo out of endosomes (Jensen et al., 2023). Andersen and colleagues have described valine-1697 as contributing to a “hydrophobic glue” that holds together the folds of the 3Fn domain, and they predicted that non-conservative substitutions at this position are moderately likely to increase AD risk (Andersen et al., 2023). Replacement of valine with the hydrophobic amino acid isoleucine is likely tolerated. Indeed, among 40 species examined, valine was found at the homologous position in 22 cases, while isoleucine occurred in this position in 18 cases (Andersen et al., 2023).

The variant was predicted to be harmless by several algorithms, including SIFT, PROVEAN, Mutation Taster, and PolyPhen-2 (Campion et al., 2019; El Bitar et al., 2019; Fernández et al., 2016; Sassi et al., 2016; Vardarajan et al., 2015; Verheijen et al., 2016).

Table

^aAllele frequencies as reported by study authors or calculated by Alzforum curators from data provided in the study, assuming heterozygosity if not explicitly stated in the paper.
^bLinkage and association analysis with PSEUDOMARKER20 using all family members and unrelated controls.

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References

Paper Citations

1. Fernández MV, Black K, Carrell D, Saef B, Budde J, Deming Y, Howells B, Del-Aguila JL, Ma S, Bi C, Norton J, Chasse R, Morris J, Goate A, Cruchaga C, NIA-LOAD family study group, NCRAD. SORL1 variants across Alzheimer's disease European American cohorts. Eur J Hum Genet. 2016 Dec;24(12):1828-1830. Epub 2016 Sep 21 PubMed.
2. Sassi C, Ridge PG, Nalls MA, Gibbs R, Ding J, Lupton MK, Troakes C, Lunnon K, Al-Sarraj S, Brown KS, Medway C, Lord J, Turton J, ARUK Consortium, Morgan K, Powell JF, Kauwe JS, Cruchaga C, Bras J, Goate AM, Singleton AB, Guerreiro R, Hardy J. Influence of Coding Variability in APP-Aβ Metabolism Genes in Sporadic Alzheimer's Disease. PLoS One. 2016;11(6):e0150079. Epub 2016 Jun 1 PubMed.
3. Holstege H, Hulsman M, Charbonnier C, Grenier-Boley B, Quenez O, Grozeva D, van Rooij JG, Sims R, Ahmad S, Amin N, Norsworthy PJ, Dols-Icardo O, Hummerich H, Kawalia A, Amouyel P, Beecham GW, Berr C, Bis JC, Boland A, Bossù P, Bouwman F, Bras J, Campion D, Cochran JN, Daniele A, Dartigues JF, Debette S, Deleuze JF, Denning N, DeStefano AL, Farrer LA, Fernández MV, Fox NC, Galimberti D, Genin E, Gille JJ, Le Guen Y, Guerreiro R, Haines JL, Holmes C, Ikram MA, Ikram MK, Jansen IE, Kraaij R, Lathrop M, Lemstra AW, Lleó A, Luckcuck L, Mannens MM, Marshall R, Martin ER, Masullo C, Mayeux R, Mecocci P, Meggy A, Mol MO, Morgan K, Myers RM, Nacmias B, Naj AC, Napolioni V, Pasquier F, Pastor P, Pericak-Vance MA, Raybould R, Redon R, Reinders MJ, Richard AC, Riedel-Heller SG, Rivadeneira F, Rousseau S, Ryan NS, Saad S, Sanchez-Juan P, Schellenberg GD, Scheltens P, Schott JM, Seripa D, Seshadri S, Sie D, Sistermans EA, Sorbi S, van Spaendonk R, Spalletta G, Tesi N, Tijms B, Uitterlinden AG, van der Lee SJ, Visser PJ, Wagner M, Wallon D, Wang LS, Zarea A, Clarimon J, van Swieten JC, Greicius MD, Yokoyama JS, Cruchaga C, Hardy J, Ramirez A, Mead S, van der Flier WM, van Duijn CM, Williams J, Nicolas G, Bellenguez C, Lambert JC. Exome sequencing identifies rare damaging variants in ATP8B4 and ABCA1 as risk factors for Alzheimer's disease. Nat Genet. 2022 Dec;54(12):1786-1794. Epub 2022 Nov 21 PubMed.
4. Vardarajan BN, Zhang Y, Lee JH, Cheng R, Bohm C, Ghani M, Reitz C, Reyes-Dumeyer D, Shen Y, Rogaeva E, St George-Hyslop P, Mayeux R. Coding mutations in SORL1 and Alzheimer disease. Ann Neurol. 2015 Feb;77(2):215-27. PubMed.
5. Holstege H, van der Lee SJ, Hulsman M, Wong TH, van Rooij JG, Weiss M, Louwersheimer E, Wolters FJ, Amin N, Uitterlinden AG, Hofman A, Ikram MA, van Swieten JC, Meijers-Heijboer H, van der Flier WM, Reinders MJ, van Duijn CM, Scheltens P. Characterization of pathogenic SORL1 genetic variants for association with Alzheimer's disease: a clinical interpretation strategy. Eur J Hum Genet. 2017 Aug;25(8):973-981. Epub 2017 May 24 PubMed.
6. Bellenguez C, Charbonnier C, Grenier-Boley B, Quenez O, Le Guennec K, Nicolas G, Chauhan G, Wallon D, Rousseau S, Richard AC, Boland A, Bourque G, Munter HM, Olaso R, Meyer V, Rollin-Sillaire A, Pasquier F, Letenneur L, Redon R, Dartigues JF, Tzourio C, Frebourg T, Lathrop M, Deleuze JF, Hannequin D, Genin E, Amouyel P, Debette S, Lambert JC, Campion D, CNR MAJ collaborators. Contribution to Alzheimer's disease risk of rare variants in TREM2, SORL1, and ABCA7 in 1779 cases and 1273 controls. Neurobiol Aging. 2017 Nov;59:220.e1-220.e9. Epub 2017 Jul 14 PubMed.
7. Campion D, Charbonnier C, Nicolas G. SORL1 genetic variants and Alzheimer disease risk: a literature review and meta-analysis of sequencing data. Acta Neuropathol. 2019 Aug;138(2):173-186. Epub 2019 Mar 25 PubMed.
8. El Bitar F, Qadi N, Al Rajeh S, Majrashi A, Abdulaziz S, Majrashi N, Al Inizi M, Taher A, Al Tassan N. Genetic Study of Alzheimer's Disease in Saudi Population. J Alzheimers Dis. 2019;67(1):231-242. PubMed.
9. Verheijen J, Van den Bossche T, van der Zee J, Engelborghs S, Sanchez-Valle R, Lladó A, Graff C, Thonberg H, Pastor P, Ortega-Cubero S, Pastor MA, Benussi L, Ghidoni R, Binetti G, Clarimon J, Lleó A, Fortea J, de Mendonça A, Martins M, Grau-Rivera O, Gelpi E, Bettens K, Mateiu L, Dillen L, Cras P, De Deyn PP, Van Broeckhoven C, Sleegers K. A comprehensive study of the genetic impact of rare variants in SORL1 in European early-onset Alzheimer's disease. Acta Neuropathol. 2016 Aug;132(2):213-24. Epub 2016 Mar 30 PubMed.
10. Jensen AM, Kitago Y, Fazeli E, Vægter CB, Small SA, Petsko GA, Andersen OM. Dimerization of the Alzheimer's disease pathogenic receptor SORLA regulates its association with retromer. Proc Natl Acad Sci U S A. 2023 Jan 24;120(4):e2212180120. Epub 2023 Jan 18 PubMed.
11. Andersen OM, Monti G, Jensen AM, deWaal M, Hulsman M, Olsen JG, Holstege H. Relying on the relationship with known disease-causing variants in homologous proteins to predict pathogenicity of SORL1 variants in Alzheimer's disease. 2023 Feb 27 10.1101/2023.02.27.524103 (version 1) bioRxiv.

Further Reading

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