Endocrine Abstracts

Introduction: Stiff-Person Syndrome (SPS) is a rare autoimmune neurological disorder that can be associated with other autoimmune diseases including type 1 diabetes mellitus (T1DM). The presence of alternative forms of autoimmune diabetes, such as latent autoimmune diabetes in adults (LADA) in SPS, is not well described.

Case Report: A 63 years old male patient, his medical and family histories were non-specific. He developed progressive rigidity in truncal and lower-limb musculature and episodic brief truncal associated to polyuro-polydipsic syndrome. MRI of the brain and spinal cord was without anomalies, the diagnosis of stiff person syndrome was suspected, an anti GAD assay was requested returning >3000 units/ml. As part of exploration of polyuro polydipsic syndrome, a glycated hemoglobin was done returning to 8%.

Discussion: Stiff-person syndrome (SPS) is a rare neurological disorder, which is an autoimmune disorder frequently associated with the presence of serum anti-glutamic acid decarboxylase (GAD) antibody. Solimena et al was the first to describe the important link between insulin-dependent diabetes mellitus, and SPS in 1988. GAD is an endogenous enzyme that catalyzes the production of γ-aminobutyric acid (GABA), a major neurotransmitter of the central nervous system, and it is also found in pancreatic beta cells. It is a common autoantigen in SPS and type1 diabetes mellitus. They are detected in 80% of patients with newly diagnosed T1DM; but the titer of anti-GAD is much higher (around 50-100 fold) in SPS than in Type1 diabetes mellitus. The presence of the autoimmune anti-GAD may lead to disruption of neuron, beta cell function and destructs insulin secretion.

Conclusion: Despite the fact that LADA and Stiff Person Syndrome are both autoimmune diseases characterized by the presence of anti-GAD, the rates of co-occurrence of SPS and LADA remain unknown.

Reference: 1. World J Clin Cases. 2019 Oct 6; 7(19): 2942–2952.