Three interesting rare diseases, described on the National Organization for Rare Disorders website, are Greig cephalopolysyndactyly syndrome (GCS), idiopathic pulmonary fibrosis (IPF) and xeroderma pigmentosum (XP). GCS causes abnormalities on the face, fingers and toes. IPF causes thickening, stiffening and scarring of lung tissue. XP causes a deficiency in the body's ability to repair damage from ultraviolet light.
Characteristics of GCS are having extra fingers (supernumerary) or toes (polydactyly), webbing between fingers and toes or fusion of them (syndactyly), a large or strangely shaped skull, frontal bossing (high forehead), a large nasal bridge, widely spaced eyes, and other physical abnormalities. The most common cause of GCS is the inheritance of a genetic trait.
IPF causes lung disorders, including shortness of breath and lung disease. However, the rate at which it progresses and its strength vary from case to case. Ultimately, the disease is life-threatening, as it causes respiratory complications. The term "idiopathic," means that the underlying cause of this disease is currently unknown. Many factors are thought to play a role.
Characteristics of XP include severe sunburn with limited exposure, early development of freckles, skin cancers and rough growths, sensitive and often clouded/bloodshot eyes and limited hair growth. Most people with the disease die before age 20. XP is a genetic disorder, and like GCS it is determined by a person's genes.