A genome-wide association study in autoimmune neurological syndromes with anti-GAD65 autoantibodies
Authors: Strippel Christine , Herrera-Rivero Marisol , Wendorff Mareike , Tietz Anja K , Degenhardt Frauke , Witten Anika , Schroeter Christina , Nelke Christopher , Golombeck Kristin S , Madlener Marie , Rüber Theodor , Ernst Leon , Racz Attila , Baumgartner Tobias , Widman Guido , Doppler Kathrin , Thaler Franziska , Siebenbrodt Kai , Dik Andre , Kerin Constanze , Räuber Saskia , Gallus Marco , Kovac Stjepana , Grauer Oliver M , Grimm Alexander , Prüss Harald , Wickel Jonathan , Geis Christian , Lewerenz Jan , Goebels Norbert , Ringelstein Marius , Menge Til , Tackenberg Björn , Kellinghaus Christoph , Bien Christian G , Kraft Andrea , Zettl Uwe , Ismail Fatme Seval , Ayzenberg Ilya , Urbanek Christian , Sühs Kurt-Wolfram , Tauber Simone C , Mues Sigrid , Körtvélyessy Peter , Markewitz Robert , Paliantonis Asterios , Elger Christian E , Surges Rainer , Sommer Claudia , Kümpfel Tania , Gross Catharina C , Lerche Holger , Wellmer Jörg , Quesada Carlos M , Then Bergh Florian , Wandinger Klaus-Peter , Becker Albert J , Kunz Wolfram S , Meyer zu Hörste Gerd , Malter Michael P , Rosenow Felix , Wiendl Heinz , Kuhlenbäumer Gregor , Leypoldt Frank , Lieb Wolfgang , Franke Andre , Meuth Sven G , Stoll Monika , Melzer Nico ,   German Network for Research on Autoimmune Encephalitis (GENERATE), Adelmann Michael , Appeltshauser Luise , Ayzenberg Ilya , Baade-Büttner Carolin , van Baalen Andreas , Baatz Sebastian , Balint Bettina , Bauer Sebastian , Baumgartner Annette , Benesch Sonka , Berger Robert , Berning Sascha , Bernsen Sarah , Bien Christian , Bien Corinna , Binder Andreas , Bittner Stefan , Bittner Daniel , Blaes Franz , Blaschek Astrid , Dargvainiene Justina , Decker Julia , Dik Andre , Doppler Kathrin , Dreesmann Mona , Ebinger Friedrich , Edelhoff Lena , Ehrlich Sven , Eisenhut Katharina , Endres Dominique , Entscheva Marina , Hartmut Faiss Jürgen , Kristin Falk Kim , Fazeli Walid , Finke Alexander , Finke Carsten , Fitzner Dirk , Flotats-Bastardas Marina , Fousse Mathias , Friedemann Paul , Friese Manuel , Gallus Marco , Gebhard Marcel , Geis Christian , Goedel Clemens , Gorsler Anna , Grau Armin , Grauer Oliver , Groß Catharina , Gül Halime , Ha-Yeun Chung , Haghikia Aiden , Handreka Robert , Hansen Niels , Häusler Martin , Havla Joachim , Heide Wolfgang , Held Valentin , Hellwig Kerstin , Hillebrand Philip , Hoffmann Frank , Hoffmann Anna , Hofstadt-van Oy Ulrich , Huppke Peter , Seval Ismail Fatme , Jansen Martina , Juranek Aleksandra , Karenfort Michael , Kaufmann Max , Kellinghaus Christoph , Kerin Constanze , Knake Susanne , Körtvélyessy Peter , Kovac Stjepana , Kraft Andrea , Krämer Markus , Krogias Christos , Kümpfel Tanja , Lehrich Christoph , Lewerenz Jan , Leypoldt Frank , Linsa Andeas , Lünemann Jan , Malter Michael , Meister Monika , Melzer Nico , Stefanie Melzer Kristin , Menge Til , Meuth Sven , Meyer zu Hörste Gerd , Mono Marie-Luise , Mues Sigrid , Nagel Michael , Nelke Christopher , Neumann-Haefelin Tobias , Obrocki Jost , Penner Loana , Kristina Pfeffer Lena , Pfefferkorn Thomas , Philipsen Alexandra , Piepgras Johannes , von Poderwils Felix , Priller Josef , Pröbstel Anne-Katrin , Prüß Harald , Maria Helena Rau Johanna , Jania Räuber Saskia , Reimann Gernot , Reinecke Raphael , Ringelstein Marius , Rohner Hendrik , Rosenow Felix , Rostasy Kevin , Rüber Theodor , Rüegg Stephan , Schaumberg Jens , Schilling Ruth , Schimmel Mareike , Schmidt Jens , Schmütz Ina-Isabelle , Schreiber Stephan , Schreyer Gesa , Schröder Ina , Schröter Christina , Schuster Simon , Seidel Günter , Senel Makbule , Siebenbrodt Kai , Sommer Claudia , Stammel Oliver , Stangel Martin , Stolze Henning , Stoppe Muriel , Storm van`s Gravesande Karin , Strippel Christine , Sturm Dietrich , Sühs Kurt-Wolfram , Syrbe Steffen , Tauber Simone , Teußer Malte , Thaler Franziska , Then Bergh Florian , Trebst Corinna , Trendelenburg George , Trollmann Regina , Tumani Hayrettin , Türedi Methab , Urbanek Christian , Vogel Niklas , von Mering Matthias , Wagner Judith , Wandinger Klaus-Peter , Weissert Robert , Wickel Jonathan , Wiendl Heinz , Wildemann Brigitte , Witt Karsten , Wunderlich Benjamin , Zieger Lara 
Published: March 2022

Autoimmune neurological syndromes (AINS) with autoantibodies against the 65 kDa isoform of the glutamic acid decarboxylase (GAD65) present with limbic encephalitis, including temporal lobe seizures or epilepsy, cerebellitis with ataxia, and stiff-person-syndrome or overlap forms. Anti-GAD65 autoantibodies are also detected in autoimmune diabetes mellitus, which has a strong genetic susceptibility conferred by human leukocyte antigen (HLA) and non-HLA genomic regions. We investigated the genetic predisposition in patients with anti-GAD65 AINS.

We performed a genome-wide association study (GWAS) and an association analysis of the HLA region in a large German cohort of 1214 individuals. These included 167 patients with anti-GAD65 AINS, recruited by the German Network for Research on Autoimmune Encephalitis (GENERATE), and 1047 individuals without neurological or endocrine disease as population-based controls. Predictions of protein expression changes based on GWAS findings were further explored and validated in the CSF proteome of a virtually independent cohort of 10 patients with GAD65-AINS and 10 controls.

Our GWAS identified 16 genome-wide significant (P &lt; 5 × 10−8) loci for the susceptibility to anti-GAD65 AINS. The top variant, rs2535288 [P = 4.42 × 10−16, odds ratio (OR) = 0.26, 95% confidence interval (CI) = 0.187–0.358], localized to an intergenic segment in the middle of the HLA class I region. The great majority of variants in these loci (&gt;90%) mapped to non-coding regions of the genome. Over 40% of the variants have known regulatory functions on the expression of 48 genes in disease relevant cells and tissues, mainly CD4+ T cells and the cerebral cortex. The annotation of epigenomic marks suggested specificity for neural and immune cells. A network analysis of the implicated protein-coding genes highlighted the role of protein kinase C beta (PRKCB) and identified an enrichment of numerous biological pathways participating in immunity and neural function. Analysis of the classical HLA alleles and haplotypes showed no genome-wide significant associations. The strongest associations were found for the DQA1*03:01-DQB1*03:02-DRB1*04:01HLA haplotype (P = 4.39 × 10−4, OR = 2.5, 95%CI = 1.499–4.157) and DRB1*04:01 allele (P = 8.3 × 10−5, OR = 2.4, 95%CI = 1.548–3.682) identified in our cohort. As predicted, the CSF proteome showed differential levels of five proteins (HLA-A/B, C4A, ATG4D and NEO1) of expression quantitative trait loci genes from our GWAS in the CSF proteome of anti-GAD65 AINS.

These findings suggest a strong genetic predisposition with direct functional implications for immunity and neural function in anti-GAD65 AINS, mainly conferred by genomic regions outside the classical HLA alleles.