does anyone have a clear definition of what down syndrome is?

Question

i know that it is an extra 21 crom. but what exactly is it? what does that extra chrom. do? why is that what causes this?

what about that extra chrom. makes the down syndrome? i know the basic deff. but i want to have a more detailed answer.

ok... answer this... WHAT IS IT ABOUT THAT EXTRA 21 CROM. THAT PRODUCES THE DOWN SYNDROME? WHAT IS DOWN SYNDROME REALLY? BESIDES THE FACT THAT IT IS CAUSED BY THE EXTRA 21 CROM.

Answer 1

Down syndrome |ˈdoun ˈsindrōm| (also Down's syndrome)
noun
Medicine a congenital disorder arising from a chromosome defect, causing intellectual impairment and physical abnormalities including short stature and a broad facial profile. It arises from a defect involving chromosome 21, usually an extra copy (trisomy-21).

ORIGIN 1960s: named after John L. H. Down (1828–96), the English physician who first described it.
USAGE Of relatively recent coinage, Down syndrome is the accepted term in modern use, and former terms such as mongol, Mongoloid, and mongolism, which are likely to cause offense, should be avoided. See also usage at Mongoloid .

Answer 2

Down syndrome or trisomy 21 (British Down's syndrome) is a genetic condition resulting from the presence of all or part of an extra 21st chromosome. Down syndrome is characterized by a combination of major and minor abnormalities of body structure and function. Among features present in nearly all cases are impairment of learning and physical growth, and a recognizable facial appearance usually identified at birth. It is named after John Langdon Down, the British doctor who first described it in 1866.

Answer 3

Down syndrome (DS) is a condition in which extra genetic material causes delays in the way a child develops, and often leads to mental retardation.