A study in the January issue of SLEEP found that participants with the human leukocyte antigen (HLA) allele DQB1*06:02 were 251 times more likely to have narcolepsy with cataplexy than participants without the common gene variant, which had a remarkably high negative predictive value of 99.32 percent. The modified genome-wide association study involved 1,261 people with narcolepsy, representing nearly 90 percent of European patients suffering from narcolepsy with cataplexy who have complete diagnostic work-up and DNA available. The results suggest that high-resolution genotyping might aid in diagnosing patients suspected of having narcolepsy, reported a HealthDay article published by U.S. News & World Report.