Research To Date Has Shown: 1  ADHD is a neurobiologic condition whose symptoms are also dependent on the child's environment. 2  A lower level of activity in the parts of the brain that control attention and activity level may be associated with ADHD. 3  ADHD frequently runs in families.
Mosaic (genetics) In genetics, a mosaic (or mosaicism) means the presence of two different genotypes in an individual which developed from a single fertilized egg. As a result, the individual has two or more genetically different cell lines derived from a single zygote. Unusual events in cell division (mitosis).
Also called mosaâ²ic disease`. any of several diseases of plants, characterized by mottled green or green and yellow areas on the leaves, caused by certain viruses. 6. an organism exhibiting mosaicism. adj. 7. pertaining to, resembling, or used for making a mosaic or mosaic work: a mosaic tile.