The Immunologic Complications and Genetic Origins of Telomere Disorders

Telomeres correspond to the ends of linear chromosomes. Their length and structure have to be tightly regulated to avoid genomic instability, cell death, or premature senescence. In humans, defective telomere maintenance causes the dyskeratosis congenita (DC) condition characterized by a bone marrow failure associated with other premature aging features such as mucocutaneous abnormalities and cancer predisposition. Hoyeraal–Hreidarsson syndrome (HH) represents the severe form of DC and consists of an early-onset bone marrow failure, immunodeficiency, intrauterine growth retardation, and cerebellar hypoplasia. DC and HH patients exhibit progressive immunodeficiency principally caused by declining bone marrow function. In this article, we review our current knowledge on the etiology of DC and HH and summarize the immunologic characteristics of DC-HH and the genes responsible for these telomere disorders.