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.
By Dr Ananya Mandal, MD. Down syndrome or Downâs syndrome is a congenital condition caused by the presence of an additional copy of chromosome 21 in a personâs cells. This is also referred to as trisomy 21. Humans usually have 46 chromosomes in every cell, with 23 inherited from each parent.Due to the extra copy of chromosome 21, people with Downâs syndrome have 47 chromosomes in their cells.t was only in the mid-twentieth century, (the 1950s) that karyotype techniques were discovered, which could be used to help identify the shape and number of chromosomes. This led to the understanding that trisomy 21 was the cause of Downâs syndrome, a finding that was reported by Jerome JÃ©rÃ´me lejeune in. 1959