find out if there are diseases which are passed on from parents to the offspring.Find out how these are carried and also if these diseases can be treated.

Genetic disorders can be inherited, in which case people are born with them, even if they are not noticeable at first. Some disorders, however, are not inherited but develop spontaneously when disease-causing mutations ^* occur during cell division ^* . These also are genetic disorders, because they involve changes in the genes.

Some inherited genetic disorders, such as cystic fibrosis ^* and phenylketonuria ^* (PKU), are caused simply by the inheritance of genes that do not work properly. In other disorders, however, genetic and environmental factors seem to work together to cause changes in otherwise normal genes. For example, some forms of radiation or chemicals can cause cancer in people who are prone to be affected because of their genetic makeup.

^* cystic fibrosis (SIS-tik fi-BRO-sis) is a genetic disorder of the body's mucus-producing glands. It mainly affects the respiratory and digestive systems of children and young adults.

^* phenylketonuria (fen-ul-ke-ton-Uree-a), or PKU for short, is a genetic disorder of body chemistry that, if left untreated, causes mental retardation.