The term pleiotropy (Greek: pleion = more) is used to describe a gene that affects more than one characteristic of the individual. A gene with multiple phenotype effects is called pleiotropic.
The genetic disorder sickle cell anemia is a classic example how the alleles at a single locus can have pleiotropic effect. There is a wide range of symptoms characteristic of an individual who is homozygous, recessive for the disorder sickle cell. (Symptoms: Blood flow to the body parts is reduced resulting in periodic fever, sever pain, damage to various organs including heart, brain, kidneys, causing anemia, paralysis, pneumonia, rheumatism, kidney failure and spleen damage.)