How did the condition Down Syndrome get its name?

From Dr. John Down, the physician who described it in1866. [ Wikipedia entry. ]

That’s why it’s called Down’s Syndrome.

Also known as Trisomy 21, it was once called “mongolism” but that term is no longer politically correct. “Down Syndrome” is more common today than “Down’s Syndrome.” Wikipedia notes that ”…Although both the possessive and non-possessive forms are used in the general population, Down syndrome is the accepted term among professionals in the U.S., Canada and other countries; Down’s syndrome is still used in the UK and other areas.”

Down Syndrome, named after Dr. John Langdon Down after his discovering it in 1866, is a cogenital disorder that results in abnormal development in the brain. Down Syndrome is not caused by the inheritance of a faulty gene but by the possession of an extra twenty-first chromosome. The syndrome is closely related to the mother’s age; in most cases something goes wrong withe some of her ova, resulting in the presence of two (rather than one) twenty-first chromosomes. When fertilization occurs, the addition of the father’s twenty-first chromosome makes three, rather than two. The extra chromosome presumably causes biochemical changes that impair normal brain development.