The loss-of-function mutations in TRPML1 directly cause the lysosomal storage disorder mucolipidosis type IV (MLIV), a neurodegenerative disease characterized by abnormal neurodevelopment, retinal degeneration, and iron-deficiency anemia (Bargal et al, 2000; Bassi et al, 2000; Gan & Jiang, 2022; Nilius et al, 2007). The gene discussed is MCOLN1; the disease is mucolipidosis type IV.