Microcephaly and megalencephaly are disorders characterized by what?

Microcephaly and megalencephaly are neurological conditions that specifically refer to abnormal brain sizes. Microcephaly is characterized by an abnormally small head and brain size, which can lead to developmental issues and intellectual disability. In contrast, megalencephaly refers to an abnormally large brain size, which can also be associated with various neurodevelopmental disorders. These conditions directly correlate with the physical size of the brain, therefore identifying them as disorders characterized by abnormal brain sizes. This distinction is important in the context of developmental biology and neurology, as it underscores the relationship between brain structure and function. The other options relate to specific cognitive or motor functions rather than directly addressing the fundamental nature of these conditions.