Overview

Clinical Phenotype: Alzheimer's Disease
Reference Assembly: GRCh37/hg19
Position: Chr11:121498424 C>A
dbSNP ID: rs143536682
Coding/Non-Coding: Coding
DNA Change: Substitution
Expected Protein Consequence: Missense
Codon Change: AGC to AGA
Reference Isoform: SORL1 Isoform 1 (2214 aa)
Genomic Region: Exon 47

Findings

In a French cohort of 852 early onset AD cases, 927 late-onset cases, and 1273 controls from the Alzheimer Disease Exome Sequencing France (ADESFR) project, one early onset case was a heterozygous carrier of this variant (Bellenguez et al., 2017).

In a study that included 15,808 Alzheimer’s cases and 16,097 control subjects from multiple European and American cohorts, including ADESFR, this allele was observed once among the AD cases (Holstege et al., 2022). No additional carriers were found when this dataset was expanded to 18,959 AD cases and 21,893 controls (Holstege et al., 2023).

Functional Consequences

Serine-2175 is located in SORL1’s cytoplasmic tail, within the ²¹⁷²FANSHY²¹⁷⁷ motif, a strictly conserved sequence necessary for binding the retromer complex (Fjorback et al., 2012). Andersen and colleagues have predicted that substitutions at this position are moderately likely to increase AD risk (Andersen et al., 2023).

Data on the functional consequences of substitutions at this specific residue are lacking. However, in vivo and in vitro studies showed that when the FANSHY domain was mutated to disrupt retromer binding, SORL1 accumulated in endosomes and was depleted from the Golgi/trans-Golgi network, while levels of APP cleavage products Aβ40, Aβ42, sAPPα, and sAPPβ increased (Fjorback et al., 2012; Dumanis et al., 2015). These findings can be explained if retromer-dependent sorting of SORL1 and its ligand APP from endosomes back to the Golgi/trans-Golgi network protects APP from processing in endosomal compartments.

The variant was predicted to be harmful by SIFT, Mutation Taster, and PolyPhen-2 (Bellenguez et al., 2017).

In a study investigating the effects of SORL1 missense mutations on protein processing, the S2175R (C>A) variant did not affect the maturation (glycosylation) of SORL1 overexpressed in HEK293 cells (Rovelet-Lecrux et al., 2021).

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References

Paper Citations

1. 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.
2. 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.
3. Holstege H, deWaal MW, Tesi N, vanderLee SJ, ADESconsortium, ADSPconsortium, StEP-ADconsortium, Knight-ADRC, UCSF/NYGC/UAB, Vogel M, vanSpaendonk R, Hulsman M, Andersen OM. Effect of prioritized SORL1 missense variants supports clinical consideration for familial Alzheimer's Disease. 2023 Jul 16 10.1101/2023.07.13.23292622 (version 1) medRxiv.
4. Fjorback AW, Seaman M, Gustafsen C, Mehmedbasic A, Gokool S, Wu C, Militz D, Schmidt V, Madsen P, Nyengaard JR, Willnow TE, Christensen EI, Mobley WB, Nykjaer A, Andersen OM. Retromer binds the FANSHY sorting motif in SorLA to regulate amyloid precursor protein sorting and processing. J Neurosci. 2012 Jan 25;32(4):1467-80. PubMed.
5. 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.
6. Dumanis SB, Burgert T, Caglayan S, Füchtbauer A, Füchtbauer EM, Schmidt V, Willnow TE. Distinct Functions for Anterograde and Retrograde Sorting of SORLA in Amyloidogenic Processes in the Brain. J Neurosci. 2015 Sep 16;35(37):12703-13. PubMed.
7. Rovelet-Lecrux A, Feuillette S, Miguel L, Schramm C, Pernet S, Quenez O, Ségalas-Milazzo I, Guilhaudis L, Rousseau S, Riou G, Frébourg T, Campion D, Nicolas G, Lecourtois M. Impaired SorLA maturation and trafficking as a new mechanism for SORL1 missense variants in Alzheimer disease. Acta Neuropathol Commun. 2021 Dec 18;9(1):196. PubMed.

Further Reading

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