The theoretical model builds on the concept of continental drift developed during the first few decades of the 20th century. The geoscientific community accepted plate-tectonic theory after seafloor spreading was validated in the late 1950s and early 1960s. The lithosphere, which is the rigid outermost shell of a planet (the crust and upper mantle), is broken up into tectonic plates.
These disorders are known as monogenetic disorders (disorders of a single gene). Some examples of monogenetic disorders include: 1  cystic fibrosis, 2  sickle cell anemia,3  Marfan syndrome, 4  Huntington's disease, and.5  hemochromatosis.ome examples of monogenetic disorders include: 1  cystic fibrosis, 2  sickle cell anemia, 3  Marfan syndrome, 4  Huntington's disease, and. 5  hemochromatosis.
1. Single gene disorders: disorders caused by defects in one particular gene, often with simple and predictable inheritance patterns. 1  Dominant diseases: single gene disorders that occur when an individual has one altered copy of the relevant gene and one healthy copy.2  For example, Huntingtonâs disease.. Multifactorial disorders (complex diseases): disorders caused by changes in multiple genes, often in a complex interaction with environmental and lifestyle factors such as diet or cigarette smoke.