- Fragile X syndrome, a form of mental retardation second in frequency only to Down syndrome. Since females have two copies of the X chromosome (whereas males have one copy of X and one copy of Y), they can be carriers of this disease, in which a part of the end of one of the 'arms' of an X chromosome is weaker and may break off. At its most severe, the syndrome resembles autism or hyperactivity; at its least severe, affected children appear perfectly normal. A poignant question implied by the text: should we find a cure for a given disease before we test? Apply this to various medical scenarios.
- In the midst of an inset on how Science News tried to frame the genetic-testing/screening debate in 1994 comes this gem (emphasis mine): "A geneticist and a genetic counselor favored giving the dwarf couple [who wanted a dwarf child] the test; two well-known ethicists said the test should not be provided. They argued that using genetic testing to help abort a healthy fetus runs counter to its purpose." Now what was it people are saying about legalized abortion leading to "every child a wanted child"?
- Another inset is titled "Mutations, Variations, and 'normality'." The main question: How do we tell whether a given gene is "normal" or not? Is the "normal" allele (form) the most common one? What if that proportion decreases as a result of population-genetics factors?
- Helpful is another inset: "What to Consider Before You're Tested." For example: "If something seems to 'run in the family,' are you sure that each relative actually had the condition you suspect?" Other suggestions include sensible ones like being as informed as possible, taking notes, keeping records, finding out costs beforehand, and collecting unbiased details about success rates of various tests, not to mention "the nature and variability of the disease...and nongenetic [sic] factors that may contribute to its development."
Wednesday, June 11, 2008
Unnatural Selection: Chapter 6
Mainly about genetic testing (not to be confused with screening, also mentioned), this chapter takes a wide sweep. Here's a sampling: