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.
1. On single gene traits: can lead to changes in allele frequencies and changes in phenotype frequencies. 2. On polygenic traits: can affect the relative fitness of phenotypes and produce one of 3 types of selection-directional, stabilizing, disruptive.