Mutations in glucocerebrosidase beta acid (GBA), SNCA and TMEM175 (that encode β-glucosylceramidase) reduce potassium current and elevate α-synuclein levels, thus impairing mitochondria and lysosomal function along with a decrease in lysosome activity and glucocerebrosidase with an increase in the risk for PD and PDD (240). Here, GBA1 is linked to Parkinson disease.