Down Syndrome or trisomy 21 (usually Down's Syndrome in British English) is a genetic disorder caused by the presence of all or part of an extra 21st chromosome. It is named after John Langdon Down, the British doctor who described it in 1866. Many of the common physical features of Down syndrome also appear in people with a standard set of chromosomes. They include a single transverse palmar crease (a single instead of a double crease across one or both palms), an almond shape to the eyes caused by an epicanthic fold of the eyelid, shorter limbs and poor muscle tone.
Find a number of official website listed here providing information and a range of resources for those with Down's syndrome, their family and carers. Please click on the website title of your choice below to enter each individual website to find further information and their contacts.