DNA repair-deficiency disorder or DNA repair disorder is a medical condition that affects the body's ability to repair damages in DNA. It is caused by the decreased efficiency of DNA repair mechanisms that may lead to genetic mutations, instability, and ultimately, diseases or cancer. There are several synonyms for DNA repair-deficiency disorder, which include DNA repair deficiency syndrome, DNA damage response deficiency, genomic instability syndrome, and DNA repair disease. These terminologies describe the same condition and generally refer to a group of rare genetic disorders that affect the body's ability to fix damages in DNA. It is important to diagnose and manage these disorders promptly to prevent potentially harmful outcomes of genomic instability.