X-linked spondyloepiphyseal dysplasia tarda is a condition that impairs bone growth and occurs almost exclusively in males. The name of the condition indicates that it affects the bones of the spine (spondylo-) and the ends of long bones (epiphyses) READ MORE

X-linked thrombocytopenia is a bleeding disorder that primarily affects males. This condition is characterized by a blood cell abnormality called thrombocytopenia, which is a shortage in the number of blood cells involved in clotting (platelets). Aff READ MORE

Xeroderma pigmentosum, commonly known as XP, is an inherited condition characterized by an extreme sensitivity to ultraviolet radiation (UVR), which is present in sunlight and may also be found in some types of artificial lighting. This condition mos READ MORE

Xia-Gibbs syndrome is a neurological disorder characterized by weak muscle tone (hypotonia), mild to severe intellectual disability and delayed development. Expressive language skills (vocabulary and the production of speech) are particularly affecte READ MORE

Y chromosome infertility is a condition that affects the production of sperm and causes male infertility, which means it is difficult or impossible for affected men to father children. An affected man's body may produce no mature sperm cells (azoospe READ MORE

Yao syndrome (formerly called NOD2 -associated autoinflammatory disease) is a disorder involving episodes of fever and abnormal inflammation affecting many parts of the body, particularly the skin, joints, and gastrointestinal system. Inflammation is READ MORE

Yuan-Harel-Lupski (YUHAL) syndrome is a rare neurological condition that has a combination of features of two other disorders, Potocki-Lupski syndrome and type 1A Charcot-Marie-Tooth disease. The first signs and symptoms of YUHAL syndrome begin in in READ MORE

ZAP70 -related severe combined immunodeficiency (SCID) is an inherited disorder that damages the immune system. ZAP70 -related SCID is one of several forms of severe combined immunodeficiency, a group of disorders with several genetic causes. Childre READ MORE

Zellweger spectrum disorder is a condition that affects many parts of the body. Cases of Zellweger spectrum disorder are often categorizes as severe, intermediate, or mild. Individuals with severe Zellweger spectrum disorder usually have signs and sy READ MORE