Other autoantibodies associated with stiff person syndrome (SPS)10–12
| Gephyrin | Present in a very small proportion of the paraneoplastic variant. It is a postsynaptic cellular protein responsible for clustering of two inhibitory neurotransmitters: (1) glycine receptors in the spinal cord and (2) GABA-A receptors in the brain. |
| Amphiphysin | Present in 5% of the paraneoplastic variant. It is a synaptic vesicle protein responsible for endocytosis of the vesicle membrane after exocytosis of GABA from the axonal terminals. |
| GABA (A) receptor-associated protein | Present in 70% of SPS patients. It is a postsynaptic protein at GABA-ergic synapses, responsible for the stability and surface expression of GABA-A receptor and organises the clustering of GABA (A)-receptor by linking them to gephyrin. |
GABA, γ-aminobutyric acid.