A disorder is a functional abnormality or disturbance. The epicanthic fold is sometimes found as a congenital abnormality. Down syndrome is the most common chromosomal abnormality in humans. Prognosis varies depending on the type of callosal abnormality and associated conditions or syndromes. Hypothyroidism is the most common thyroid abnormality associated with PFAS exposure. Bullying may also result from a genetic predisposition or a brain abnormality in the bully. A common associated brain abnormality is mesial temporal sclerosis. Most eunuchs were born as such with a congenital abnormality. Down syndrome is the most common chromosome abnormality in humans. The exchanger is also implicated in the cardiac electrical conduction abnormality known as delayed afterdepolarization. Frontal lobe abnormality and psychosis in traumatic brain injury and cannabis abuse. Hereditary spherocytosis is an abnormality of red blood cells, or erythrocytes. The impetus was the loss of her own unborn child diagnosed with a genetic abnormality. Obstructive physiology is the most common abnormality. In 1964, it was determined to be due to a chromosomal abnormality.