Genes are segments of DNA, the long molecules that reside in each of a person's cells. The genes, through complex processes, build proteins for growth and maintenance of the body. At conception, DNA-or genes-from both parents are passed to the child. A genetic disease occurs when one or both parents pass abnormal genes to a child at conception. If receiving an abnormal gene from just one parent is enough to produce a disease in the child, the disease is said to have dominant inheritance. If receiving abnormal genes from both parents is needed to produce disease in the child, the disease is said to be recessive. A genetic disease can also occur through a spontaneous mutation. The chance of acquiring a dominant disease is higher than the chance of acquiring a recessive disease. A child who receives only one gene copy for a recessive disease at conception will not develop the genetic disease-such as autosomal recessive PKD-but could pass the gene to the following generation.