An outstanding example is the discovery that the carriers of glucosylceramidase β1 (GBA1) gene mutations typically show an earlier age at onset and a more aggressive disease course, correlated with a greater probability of developing cognitive impairment, neurobehavioral issues, REM sleep behavior disorder, and other nonmotor symptoms, as well as postural instability and falls. Here, GBA1 is linked to Cognitive impairment.