Antibody targets in SPS
| Antibodies | % positivity in SPS | Presentation |
| GAD | 75%–80% | Classical SPS, SPS plus |
| Amphiphysin | ~5% | Paraneoplastic SPS, PERM (less known), encephalopathy, myelopathy, cerebellar ataxia, neuropathy |
| Glycine alpha1 receptor | 10%–15% of classical SPS | PERM, partial SPS, seizures associated with high titres, chronic course. Glycine receptor alpha 1—IgG can predict response to immunotherapy 55 |
| Gephyrin | 1 case report | SPS plus (encephalitis and epilepsy) |
| DPPX | 3% | SPS plus (ataxia, hyperekplexia, autonomic, sensory, cognitive impairment, PERM (less known). Progressive course. CSF lymphocytic with intrathecal IgG production. Good response to immunotherapy, titres correlate with disease course |
| GABARAP antibodies | 70% SPS | |
| Zic4 | 1 patient reported in a case series | Fluctuating eye lid ptosis and laryngeal spasms causing a stridor49 |
CSF, cerebrospinal fluid; DPPX, di-peptidyl-peptidase like protein 6; GABARAP, GABA receptor-associated protein; GAD, glutamic acid decarboxylase; PERM, progressive encephalomyelitis with rigidity and myoclonus; SPS, stiff-person syndrome.