Background: DNA ligase IV (LIG4) deficiency is a rare autosomal recessive disorder caused by mutations in the DNA LIG4 gene. Nowadays hematopoietic stem cell transplantation(HSCT) is the most effective treatment option. Matched sibling or unrelated donor was the best choice for those patients. However, it will be a problem for LIG4 deficiency patients without proper donor as above but needed urgent transplantation because of infection or bone marrow failure. Furthermore, mixed donor chimerism after transplantation is more common in LIG4 deficiency patients because of reduced intensity conditioning(RIC) regimen. How to deal with those problems? Here we report a case which the patient received haploidentical HSCT and got complete donor chimerism after donor stem cell infusion.
Results:The patient was diagnosed as LIG4 deficiency at 8-month-old. At 14 months of age, she received a T cell receptor(TCR)α/β and CD19+ B cells depleted graft from his haploidentical father, followed a RIC regimen with no additional graft versus host disease(GvHD) prophylaxis. Engraftment was as usual. However, mixed donor chimerism occurred after transplantation and viremia persisted. Cryopreserved donor cell infusion was initiated. The chimerism grew up steadily and viremia disappeared at four months post transplantation.
Conclusions: This case report gives an example of successful haploidentical transplantation and donor stem cell infusion as a treatment option in a mixed donor chimerism situation after HSCT in LIG4 deficiency patients.