A new report shows the brains of autistic children, who suffer from the disorder tied to a combination of contributing factors from genes to the environment, have differences in regions that develop during the mother's second trimester of pregnancy.
Complement component 4 is a blood test that measures the activity of a certain protein that is part of the complement system. The complement system is a group of proteins that move freely through your bloodstream.
Healthcare providers often order a complement C3 test along with a complement C4 test. In certain diseases, both components are low, but in others only one component is low. In lupus, both C3 and C4 levels are usually low.