A case report of an adolescent with ligase-4 deficiency and the potential dangers of ionizing radiation in this rare patient population.

DNA ligase IV deficiency is a rare disorder characterized by mutations in the LIG4 gene. Mutations in this gene cause a wide array of phenotypes, many of which are fatal early in life. We present an adolescent patient with heterozygous LIG4 mutations and the T-B-NK+ DNA ligase IV phenotype. Pelvic ultrasound and magnetic resonance imaging was completed to assess the patient's amenorrhea and delayed puberty, which demonstrated an atrophic cervix, distal vagina, and uterus without direct visualization of the ovaries. Early diagnosis of DNA ligase IV deficiency is important to minimize exposure to ionizing radiation from radiologic studies and preferentially utilize imaging studies that do not require ionizing radiation, such as ultrasonography and magnetic resonance imaging.