Novel compound heterozygous DNA ligase IV mutations in an adolescent with a slowly-progressing radiosensitive-severe combined immunodeficiency.

We herein describe a case of a 17-year-old boy with intractable common warts, short stature, microcephaly and slowly-progressing pancytopenia. Simultaneous quantification of T-cell receptor recombination excision circles (TREC) and immunoglobulin κ-deleting recombination excision circles (KREC) suggested very poor generation of both T-cells and B-cells. By whole exome sequencing, novel compound heterozygous mutations were identified in the patient's DNA ligase IV ( LIG4 ) gene. The diagnosis of LIG4 syndrome was confirmed by delayed DNA double-strand break repair kinetics in γ-irradiated fibroblasts from the patient and their restoration by an introduction of wild-type LIG4 . Although the patient received allogeneic hematopoietic stem cell transplantation from his haploidentical mother, he unfortunately expired due to an insufficiently reconstructed immune system. An earlier definitive diagnosis using TREC/KREC quantification and whole exome sequencing would thereby allow earlier intervention, which would be essential for improving long-term survival in similar cases with slowly-progressing LIG4 syndrome masked in adolescents. [ABSTRACT FROM AUTHOR]