Therefore, despite up to 1000 different genes thought to contribute to increased risk of ASD, all of them eventually affect normal neural development and connectivity between different functional areas of the brain in a similar manner that is characteristic of an ASD brain. Some of these genes are known to modulate production of the GABA neurotransmitter which is the main inhibitory neurotransmitter in the nervous system. These GABA-related genes are under-expressed in an ASD brain. On the other hand, genes controlling expression of glial and immune cells in the brain e.g. astrocytes and microglia, respectively, are over-expressed which correlates with increased number of glial and immune cells found in postmortem ASD brains. Some genes under investigation in ASD pathophysiology are those that affect the mTOR signaling pathway which supports cell growth and survival.All these genetic variants contribute to the development of the autistic spectrum; however, it cannot be guaranteed that they are determinants for the development.Autism may be under-diagnosed in women and girls due to an assumption that it is primarily a male condition, but genetic phenomena such as imprinting and X linkage have the ability to raise the frequency and severity of conditions in males, and theories have been put forward for a genetic reason why males are diagnosed more often, such as the imprinted brain hypothesis and the extreme male brain theory. Early life
Several prenatal and perinatal complications have been reported as possible risk factors for autism.
However, it is the environment that impacts their visual function rather than their neurology or capacity for vision at that moment. A persons change in visual function when processing visual information in a complex environment, or trying to process a certain complex or unfamiliar visual target likely accounts for what looks like their visual ability changing from one day to the next, or from minute to minute. Feeling tired or unwell may also compound this challenge. For some people with CVI the complexity of the environment, including variables like the complexity and familiarity of the visual input, or processing various forms of secondary sensory input (for instance, sound or touch) may cause them to have difficulty using their vision to their full potential. The amount of sensory input an individual can tolerate without impacting function significantly may change throughout development and person to person. Managing fatigue may reduce fluctuations but does not eliminate them, however utilizing breaks and being well rested may help to increase resilience during these times. Addressing these changes may mean adapting strategies that work for the individual person. For example, When undertaking critical activities, people with CVI should be prepared for their vision to fluctuate, by taking precautions such as always carrying a white cane, if they use one, even if they dont always use it to the fullest. Another example is having very large print available, just in case its needed (For example, consider the consequences of losing vision while giving a public speech).