0415 Does HLA DQB1*0602 testing at our center improve the management of the patient with suspect narcolepsy? A quality improvement project

Abstract

Abstract Introduction The gene DRB1*06:02, a subtype of the DQ6 antigen, has been identified as the DQ6 subtype with the strongest association with narcolepsy type 1 (NT1). As many as 98% of patients diagnosed with narcolepsy-cataplexy are positive for DQB1*06:02. However, DQB1*06:02 has a prevalence of 12-38% in the general population and is commonly found in individuals without NT1. Testing for DQB1*06:02 may still be helpful in the diagnosis of patients with symptoms characteristic of narcolepsy owing to its high negative predictive value of 99%. When ordered appropriately, HLA-testing may reduce unnecessary sleep studies on patients. Methods All patients who underwent genetic testing for HLA DQB1*06:02 at our institution between 2015 and 2021 were included (n=8). A retrospective chart review was conducted to gather data on age, gender, total sleep time, apnea-hypopnea index, sleep efficiency, sleep latency, rapid eye movement (REM) latency, mean sleep latency, sleep-onset REM episodes, HLA DQB1*06:02 result, ordering specialty, whether genetic testing was performed before or after multiple sleep latency test (MSLT) and the final diagnosis. These parameters were evaluated in all patients to determine the utility of genetic testing in narcolepsy. Results The patients’ age ranged from 15 to 83 years old and 6 of 8 patients (75%) were male. 38% of tested patients were positive for HLADQB1*06:02. One patient with narcolepsy type 1 by MSLT was negative for HLA DQB1*06:02. 1 of 3 patients (33%) with a positive HLA DQB1*06:02 proceeded to have an MSLT performed at our institution. The ordering specialty was neurology in 7of 8 (87.5%) patients. Conclusion HLA DQB1*06:02 testing should not be ordered on patients with an MSLT consistent with narcolepsy. If a high index of suspicion for narcolepsy is present and HLA DQB1*06:02 testing is ordered, a positive result should be followed by an MSLT as it was uncertain an MSLT was ever obtained anywhere in these patients. Genetic testing with HLA DQB1*06:02 did not change management in any of the patients where it was performed. Consultation with a sleep specialist prior to performing HLA DQb1*06:02 testing to determine its medical necessity may be a cost-effective strategy. Support (If Any) none