Late-Onset Spinocerebellar Ataxia 2 with Only 32 CAG Repeats

Na, Seunghee; Kim, Taewon; Kim, Seong-Hoon; Hong, Yun Jeong

doi:2026.44.3.231

J Korean Neurol Assoc > Volume 44(3); 2026 > Article

Case Report

Journal of the Korean Neurological Association 2026;44(3): 231-233. doi: https://doi.org/10.17340/jkna.2026.0003

32회 CAG 반복만을 가진 환자에서 발생한 늦은 발병 척수소뇌실조증 2형

나승희¹, 김태원¹, 김성훈², 홍윤정²

¹가톨릭대학교 의과대학 인천성모병원 신경과
²가톨릭대학교 의과대학 의정부성모병원 신경과

Late-Onset Spinocerebellar Ataxia 2 with Only 32 CAG Repeats

Seunghee Na MD¹, Taewon Kim MD, PhD¹, Seong-Hoon Kim MD, PhD², Yun Jeong Hong MD, PhD²

¹Department of Neurology, Incheon St. Mary’s Hospital, College of Medicine, The Catholic University of Korea, Seoul, Korea
²Department of Neurology, Uijeongbu St. Mary’s Hospital, College of Medicine, The Catholic University of Korea, Seoul, Korea

Corresponding Author: Taewon Kim ,Tel: +82-32-280-5010, Fax: +82-32-280-5244, Email: kimtaewon79@gmail.com

Received: January 4, 2026 Revised: April 16, 2026 Accepted: April 27, 2026 Published online: August 1, 2026

Abstract

Spinocerebellar ataxia type 2 (SCA2) is an autosomal dominant disorder caused by CAG trinucleotide repeat expansion in the ATXN2 gene. Only a few SCA2 patients with intermediate alleles (32-34 repeats) have been reported. Herein, we describe a patient confirmed to have SCA2 with 32 CAG repeats in ATXN2. A 66-year-old man presented with progressive unsteadiness and dysarthria for several months. Brain magnetic resonance imaging (MRI) showed diffuse cerebellar atrophy, and genetic analysis confirmed 32/22 CAG repeats in ATXN2. CAG repeat counts in ATXN2 are typically approximately 22 in 90% of the general population, with very low polymorphism. These findings suggest that even a minimal expansion beyond the normal upper limit may be sufficient to cause disease, albeit with a markedly delayed onset.

Key Words: Spinocerebellar ataxias | Trinucleotide repeat expansion | Cerebellar degeneration