CNTNAP2 and multiple system atrophy: In the early stage of the patient’s illness, due to the absence of definitive diagnostic evidence for MSA, and given a previous case report describing isolated cerebellar ataxia with a CASPR2 antibody titer of 1:100 (Chen et al., 2024), clinicians initially leaned toward considering CASPR2-related diseases as a possible diagnosis based on clinical manifestations and epidemiological characteristics.