A disease, to be classified as rare, it must affect a very small percentage of the population. This percentage may vary, albeit slightly, in Europe, for example, is equal to 0.05%, while in the United States to 0.08%. The majority of rare diseases in the world interested in the field of genetics, in fact, mostly it comes to alterations or malformations of various DNA or, in particular, of the nucleic acid. The diagnosis of this type of disease is very complex and a guide to the main rare diseases can be useful.

A rare disease whose onset is between 4 and 6 years old, so in childhood, is called OPTIC ATROPHY GENETICS. There is one most common type and the demonstrations and a lighter, however, more severe and less frequent, rare. The patients to whom it is diagnosed are only 1 in 50,000. There is a progressive decrease of the view that, however, is not associated to neurological defects. The transmission occurs in a gene through gene is recessive and dominant.


The SYNDROME Bazex-Dupre-Christol is a rare inherited skin disorders, are deferred and only a hundred cases, mostly in France and Belgium . Onset occurs in infancy and is manifested by hypotrichosis, curiosity, and basal cell carcinoma. The transmission is dominant. For this disease is not indicated but radiotherapy, but may prove effective surgery on basal cells. The acrocephalosyndactyly is a syndrome that presents with idiosyncratically and malformations of various kinds. In only one family were described five cases of two generations. Other characterizations of the disease are: characteristics ears, short columella and malformations in the toes. Patients treated with octogenarian have developed mental retardation.

The SYNDROME arterial tortuosity is a rare disease of the connective tissue. The medium and large arteries have a tendency to form the enuresis because of their tortuosity. less than 80 cases are known worldwide and the female to male ratio is 1 : 1. Onset occurs in childhood and is characterized by high blood pressure in the right ventricle, acute respiratory symptoms, ventricular hypertrophy and heart failure. Patients also undergo ischemic episodes. To be diagnosed, this syndrome, needs assessments such as electrocardiography, hagiography, MRI and CT scans. 12% of patients die before age 5 due to respiratory failure, heart attacks and myocardial.