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.
Because their effects add up to influence the phenotype. When genes interact additively, the phenotype usually reflects the contributions of every gene that is involved. Height, hair curliness, skin color, are usually the result of additive genes. Dominant-recessive genes are nonadditive, the dominant gene usually controls the characteristic even when a recessive gene is the other half of a pair.