Spectrum of neurological manifestations, existence of diabetes mellitus, and 5-year mortality and cancer association outcomes in a cohort of Omani patients with positive anti- GAD autoimmunity.

Objectives: There is scarce data in the literature concerning the anti-GAD65 antibodies (GAD-Abs) autoimmunity in the Omani population.

Methods: Retrospective cohort study included GAD-Abs positive patients (n = 444) presented to a tertiary referral center in Oman from January 2005 until January 2018, with a five-year follow-up to study the cancer association and mortality outcomes.

Results: Out of 444 patients, 27 patients (6.1%) showed GAD-Abs related neurological disorders. Adult age group was significantly associated with more GAD-Abs related neurological manifestations compared to pediatric and adolescents age group (p = 0.045). There was no association between the presence or absence of neurological manifestations with diabetes mellitus nor the titer level of GAD-Abs. Refractory status epilepticus and stiff person syndrome were the main causes of death in patients with neurological manifestations over five years and none of them found to have associated cancer.

Conclusion: The GAD-Abs autoimmunity represents a spectrum of neurological manifestations with variable severity and outcome among Omanis with positive GAD-Abs testing. The results of this study will serve as a platform for future studies to address the impact of GAD-Abs autoimmunity on the morbidity, mortality and treatment efficacy in the Omani population.