Polymorphic compounds and uses thereof

A method of treating a disease, disorder, or condition selected from depression, treatment-resistant depression, a lysosomal storage disorder, juvenile neuronal ceroid lipofuscinosis (JNCL), cystinosis, Fabry disease, mucolipidosis type IV (MLIV), mental retardation or a genetic form of autism in a patient in need thereof,

• comprising administering to the patient in need thereof an effective amount of a crystalline form of compound A:
• or composition thereof, wherein the crystalline form is selected from the group consisting of Form A of compound A, Form B of compound A, and Form C of compound A;
• and wherein:
• Form A of compound A is characterized by peaks in its XRPD pattern at about 4.4, about 16.2, about 17.3, about 17.5, and about 17.7 degrees 2-theta;
• Form B of compound A is characterized by peaks in its XRPD pattern at about 5.0, about 6.2, about 15.2, about 17.5, and about 17.8 degrees 2-theta;
• and
• Form C of compound A is characterized by peaks in its XRPD pattern at about 7.0, about 16.1, about 16.3, about 19.3, and about 19.5 degrees 2-theta.