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A congenital disorder arising from a chromosome defect, causing intellectual impairment and physical abnormalities including short stature and a broad facial profile.

These are 5 symptoms.
flat facial features.small head and ears.short neck.bulging tongue.eyes that slant upward.Causes
In more than 90% of cases, the extra copy of chromosome 21 comes from the mother in the egg.In about 4% of the cases, the father provides the extra copy of chromosome 21 through the sperm.In the remaining cases, the error occurs after fertilization, as the embryo grows.