what is dyskeratosis congenita and hoyeraal hreidarsson syndrome
Hoyeraal-Hreidarsson syndrome Hoyeraal-Hreidarsson syndrome (HHS) is a very rare multisystem X-linked recessive disorder characterized by excessively short telomeres and is considered a severe form of dyskeratosis congenita.[1][2] Being an X-linked disorder, HHS primarily affects males. Patients with HHS typically present in early childhood with cerebellar hypoplasia, immunodeficiency, progressive bone marrow failure, and intrauterine growth retardation.[1] The primary cause of death in HHS is bone marrow failure, but mortality from cancer and pulmonary fibrosis is also significant.[3][4]