Alternative numbers connecting you to the same Sky helpline include: 0800 151 0775 â This is a freephone number. Calls to this number are completely free and donât consume time from your free minutes allowance. 0843 504 7160 â This is a âlo-call rateâ service number.
From what is known about the causes of Down syndrome, environmental factors and parents' behavioral activity do not seem to play a role. The causes of Down syndrome are genetic problems related to chromosome 21. While Down syndrome is genetic in that it involves an extra chromosome 21, it is not usually hereditary in the conventional sense.
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