Definition. Sex-linked diseases are passed down through families through one of the X or Y chromosomes. X and Y are sex chromosomes. Dominant inheritance occurs when an abnormal gene from one parent causes disease even though the matching gene from the other parent is normal.The abnormal gene dominates.efinition. Sex-linked diseases are passed down through families through one of the X or Y chromosomes. X and Y are sex chromosomes. Dominant inheritance occurs when an abnormal gene from one parent causes disease even though the matching gene from the other parent is normal.
Savant syndrome is a rare syndrome in which people with poor mental development or brain injury possess extraordinary mental skills which are difficult to explain scientifically. Sometimes the talents of a savant may go unnoticed.he exact cause of a savant syndrome is not known. A lot of hypotheses have been proposed. Some researchers believe that there is damage to the left hemisphere of brain, which results in compensatory changes in the right side of brain.
Causes and symptoms. DiGeorge syndrome is caused either by inheritance of a defective chromosome 22 or by a new defect in chromosome 22 in the fetus. The type of defect that is involved is called deletion. A deletion occurs when the genetic material in the chromosomes does not recombine properly during the formation of sperm or egg cells. The deletion means that several genes from chromosome 22 are missing in DiGeorge syndrome patients.