Word Origin and History for mesopotamian. ancient name for the land that lies between the Tigris and Euphrates rivers (in modern Iraq), from Greek mesopotamia (khora), literally a country between two rivers, from fem. of mesopotamos, from mesos middle (see medial (adj.)) + potamos river (see potamo-).
Monogenic forms, caused by a single mutation in a dominantly or recessively inherited gene, are well-established, albeit relatively rare types of PD. They collectively account for about 30% of the familial and 3%â5% of the sporadic cases.
A polygenic trait, is a trait that nonallelic genes control. These traits result from one or more genes contributing to the phenotype. An individual's physical appearance is determined by chromosomal inheritance and genotypic ratio. This phenomenon is known as Mendel's Laws of Inheritance.