PSYC 311 Chapter Notes - Chapter 15.6: Down Syndrome, Intellectual Disability, Amniocentesis
9 Jun 2016
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Down syndrome is a congenital- meaning you are born with it (vs. genetic) disorder that results in abnormal development of the brain, producing mental retardation in varying degrees. Down syndrome is caused by the possession of an extra 21st chromosome- in fact, a small region of the 21st chromosome with about 300 genes contains the critical region. This presumably causes biochemical changes impair normal brain development. Amniocentesis allows physicians to identify fetal cells with chromosomal abnormalities and determine whether a fetus carried down syndrome. Down syndrome occurs in about 1 out of 700 births, and people with down syndrome can be recognized from a number of characteristics. They have round heads, thick, protruding tongues that tend to keep the mouth open much of the time; short stature; low-set ears; and somewhat slanting eyelids. They are slow to learn to talk, though most learn by age five.
