Pyruvate Kinase Deficiency is a rare blood disorder where the body doesn't make enough pyruvate kinase, a protein needed for red blood cells. This study is a **global registry** to collect and study data from patients with this condition. It isn't a treatment study, so no new medicines will be tried. Instead, it will collect information over time to understand the disease better. The study will last up to 9 years, and participants will be asked to visit their doctor at least once a year for data collection. This data will help doctors learn more about how to manage and treat the disease.

• The study lasts up to 9 years with annual visits.
• Participants must have a confirmed diagnosis of PK deficiency.
• No new treatments will be tested in this study.