The purpose of this study is to determine the safety and efficacy of mitapivat in patients with sickle cell disease. Patients will be randomly assigned (like flipping a coin) in a 1:1:1 ratio to receive 50mg mitapivat, 100mg mitapivat or matched placebo for twice-daily oral administration. This means that you have a higher chance of receiving mitapivat than placebo. For every 2 patients that receive mitapivat, 1 patient will receive placebo. Study duration is 12 weeks. For taking part in this research, participants may be paid up to a total of $1350.00 if phase 2 (27 total visits). Compensation will be broken down as follows for each completed visit: $50.00 for site visit where you have to come to clinic $25.00 for any home health visit

You may be eligible for this study if you meet the following criteria:

• Conditions: Medical Research
• Age: 99 years or below
• Gender: All