A meta‐analysis showed that there was a significant differential effect of severe versus mild GBA mutations on the risk and age at onset (AAO) of PD, and the odds ratio for PD ranged between 2.84 and 4.94 for mild GBA mutations and 9.92 and 21.29 for severe GBA mutations with a 5‐year earlier AAO for severe mutations.11 The gene discussed is GBA1; the disease is Parkinson disease.