Abstract
Autoimmunity targeting the 65 kilodalton (kDa) isoform of glutamic acid decarboxylase (GAD65) encompasses common autoimmune disorders, such as type 1 diabetes, but also relatively rare neurological disorders, such as stiff-person syndrome (SPS) and cerebellar ataxia. Seropositivity for GAD65 antibody is common in the general population. The significance of GAD65 antibody needs to be interpreted in the overall clinical context of the patient under evaluation. In this monograph we will describe the background and pathophysiological context of GAD65 autoimmunity, the spectrum of neurological disorders that are encountered, diagnosis and management.

OBJECTIVES
Upon completion of this journal review, the reader will acquire skills to: 1) To recognize the spectrum of neurological and non‐neurological diseases associated with GAD65 antibody; 2) to interpret the likely clinical significance of GAD65 antibody on the basis of antibody titer; 3) to consider additional serologies pertinent to stiff‐person syndrome; 4) to select appropriate cancer tests where necessary; 5) to select appropriate symptomatic and immune therapies

ACCREDITATION STATEMENT
The AANEM is accredited by the Accreditation Council for Continuing Medical Education (ACCME) to provide continuing medical education for physicians.

DISCLOSURE INFORMATION
Andrew McKeon receives research support from Medimmune, Euroimmun, and the Mayo Clinic (Center for Individualized Medicine and Department of Laboratory Medicine and Pathology). He also has consulted for Medimmune, Euroimmun, and Grifols without personal compensation and is on the Advisory Committee for Medimmune. Ari Breiner, MD, of the 2015-2016 Monograph/Issues and Opinion Committee, receives education grants and research funding from Grifols. Any conflicts of interest have been resolved according to ACCME standards. All other authors/planners of this activity had nothing to disclose.

CREDIT DESIGNATION
The AANEM designates this enduring material for a maximum of 2.0 AMA PRA Category 1 Credits ^TM. Physicians should claim only the credit commensurate with the extent of their participation in the activity.

CME has expired for this monograph.

Drs. Andrew McKeon and Jennifer A. Tracy