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Lookup NU author(s): Dr Marta Bertoli
This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).
© 2023 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.Background: The ITPR1 gene encodes the inositol 1,4,5-trisphosphate (IP3) receptor type 1 (IP3R1), a critical player in cerebellar intracellular calcium signaling. Pathogenic missense variants in ITPR1 cause congenital spinocerebellar ataxia type 29 (SCA29), Gillespie syndrome (GLSP), and severe pontine/cerebellar hypoplasia. The pathophysiological basis of the different phenotypes is poorly understood. Objectives: We aimed to identify novel SCA29 and GLSP cases to define core phenotypes, describe the spectrum of missense variation across ITPR1, standardize the ITPR1 variant nomenclature, and investigate disease progression in relation to cerebellar atrophy. Methods: Cases were identified using next-generation sequencing through the Deciphering Developmental Disorders study, the 100,000 Genomes project, and clinical collaborations. ITPR1 alternative splicing in the human cerebellum was investigated by quantitative polymerase chain reaction. Results: We report the largest, multinational case series of 46 patients with 28 unique ITPR1 missense variants. Variants clustered in functional domains of the protein, especially in the N-terminal IP3-binding domain, the carbonic anhydrase 8 (CA8)-binding region, and the C-terminal transmembrane channel domain. Variants outside these domains were of questionable clinical significance. Standardized transcript annotation, based on our ITPR1 transcript expression data, greatly facilitated analysis. Genotype–phenotype associations were highly variable. Importantly, while cerebellar atrophy was common, cerebellar volume loss did not correlate with symptom progression. Conclusions: This dataset represents the largest cohort of patients with ITPR1 missense variants, expanding the clinical spectrum of SCA29 and GLSP. Standardized transcript annotation is essential for future reporting. Our findings will aid in diagnostic interpretation in the clinic and guide selection of variants for preclinical studies. © 2023 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.
Author(s): Tolonen JP, Parolin Schnekenberg R, McGowan S, Sims D, McEntagart M, Elmslie F, Shears D, Stewart H, Tofaris GK, Dabir T, Morrison PJ, Johnson D, Hadjivassiliou M, Ellard S, Shaw-Smith C, Znaczko A, Dixit A, Suri M, Sarkar A, Harrison RE, Jones G, Houlden H, Ceravolo G, Jarvis J, Williams J, Shanks ME, Clouston P, Rankin J, Blumkin L, Lerman-Sagie T, Ponger P, Raskin S, Granath K, Uusimaa J, Conti H, McCann E, Joss S, Blakes AJM, Metcalfe K, Kingston H, Bertoli M, Kneen R, Lynch SA, Martinez Albaladejo I, Moore AP, Jones WD, Becker EBE, Nemeth AH
Publication type: Article
Publication status: Published
Journal: Movement Disorders
Year: 2023
Pages: epub ahead of print
Online publication date: 14/11/2023
Acceptance date: 16/10/2023
Date deposited: 04/12/2023
ISSN (print): 0885-3185
ISSN (electronic): 1531-8257
Publisher: John Wiley and Sons Inc
URL: https://doi.org/10.1002/mds.29651
DOI: 10.1002/mds.29651
PubMed id: 37964426
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