2007-03-24 16:12:53 · 6 answers · asked by lanalang 5 in Science & Mathematics ➔ Biology
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 first described it in 1866. The condition is characterized by a combination of major and minor differences in body structure. Often Down syndrome is associated with some impairment of cognitive ability and physical growth as well as facial appearance. Down syndrome is usually identified at birth.
2007-03-24 16:22:59 · answer #1 · answered by Link 3 · 0⤊ 0⤋
Having a third copy of the 21st chromosome. Down Syndrome is also called Trisomy 21 for that very reason.
2007-03-24 23:16:03 · answer #2 · answered by Brian L 7 · 0⤊ 0⤋
An extra chromosome. When you're born, you have 46 chromosomes, but someone with Down Syndrome have 47.
2007-03-24 23:32:25 · answer #3 · answered by Anonymous · 0⤊ 0⤋
aquiring of an extra 47th chromosome in the 21st pair
2007-03-25 12:08:01 · answer #4 · answered by Jan 2 · 0⤊ 0⤋
due to mitotic non-disjunction, i.e. non separation of chromosome during mitosis that leads to trisomy-21..
2007-03-25 10:20:23 · answer #5 · answered by sameer c 1 · 0⤊ 0⤋
trisomy 23.Double chromosomal malfunction
2007-03-24 23:16:27 · answer #6 · answered by ebiyedinak 3 · 0⤊ 2⤋