PSYC 391 Lecture 6: Psyc 391 - Week 6 Down Syndrome
8 Feb 2017
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Document Summary
John langdon down: physician, published descriptions of people with down syndrome as a distinct group. Jerome lejeune: physician, down syndrome as a chromosomal condition. In 2000, an international team of scientists successfully identified and catalouged each of the approximately 329 genes on chromosome 21. 90-95% of all cases: 75% egg, 25% sperm carries extra genetic material translocation, part of the chromosome 21 attached to another chromosome. Hereditary: passed on by mother or father, mosaicism. Person received extra chromosome at fertilization but later during cell division the extra chromosome is lost. Only some of the body cells have additional genetic material. 2-5% of all cases: not hereditary. Not passed on by mother and father. Screening is the detection of risk factors or early signs of abnormalities in a healthy population: signs or symptoms may not be apparent. Diagnosis is the confirmation of a disorder usually in a screen positive subgroup of the population: many may show symptoms of the disorder.
