The investigate will conduct a cohort study to compare the growth and development, metabolism, lifestyle behavior, and health-related quality of life among three groups: children with transfusion-dependent β-thalassemia (TDT) who have received gene therapy, TDT children with lifelong supportive therapy and healthy children.

Inclusion Criteria:

Gene therapy group-inclusion

• Male or female age of 3-14 years
• TDT Children who have received gene therapy.
• Subjects who are willing and able to provide written informed consent.

Supportive therapy group-inclusion

• Gender same as the matched case
• Age similar to the matched case
• Children with β-TDT
• No history of gene therapy or allogeneic hematopoietic stem cell transplantation
• Subjects who are willing and able to provide written informed consent.

Healthy children group-inclusion

• Gender same as the matched case
• Age similar to the matched case
• Subjects who are willing and able to provide written informed consent.

Exclusion Criteria:

• Diagnosis of compound α-thalassemia
• Uncontrolled systemic fungal, bacterial, or viral infection
• History of malignant solid tumors, myeloproliferative or immunodeficiency diseases
• Diagnosed with mental illness
• Patients considered to be ineligible for the study by the investigator for reasons other than the above

Discontinuation of Study :

• Subjects who are unwilling or unable to continue participating in the study (withdrawal of informed consent) may withdraw from the study
• Subjects who received gene therapy or allogeneic hematopoietic stem cell transplantation during the study
• The subject is seriously non-compliant with the study requirements, such as missing 2 consecutive visits
• Subject lost to follow-up

Participants are divided into three groups: TDT children who have received gene therapy, TDT children who have received lifelong supportive therapy, and healthy children.