However, while we observed no significant differences between the performance of one month-old wild-type and Mcoln1−/− mice, these mutant mice fail to undergo the normal developmental progression and showed significantly decreased jumping, rearing and exploratory activity at two months compared to their control littermates, indicating an onset of the locomotor and potentially cognitive decline due to the loss of TRPML1 at this age. The gene discussed is MCOLN1; the disease is Mental deterioration.