Page 220

can be directed at any tumor, genetic or not.

Exploring the ethics of germline gene therapy You can see that the range of techniques for using genetic engineering to cure disease is enormous. Scientists are discovering new methods of delivering healthy genes to replace disease-conferring genes as you read this book. This approach would certainly be the simplest and most successful way of treating the diseases provoked by inheritance of a single dominant gene. However, this type of treatment would cure only the particular individual without affecting the transmission of the disease to his offspring. To eliminate the disease from future generations, genetic engineering has to take place in the sperm and/or the egg, the germline of the individual. Germline gene therapy raises tremendous ethical questions. If we have the tools for eliminating the recessively inherited Pendred syndrome by replacing a Pendred gene with a normal gene, don’t we also have the tools for changing skin color, height, or any other body characteristic in future generations? An entire field of genetics concerns ELSI, the ethical, legal, and social implications of genetic science. So far, germline gene therapy has actually been successful in some animals, but hasn’t been done on humans for several reasons: The methods used so far are very imprecise, so the final product is uncertain, including the possible introduction of harmful genes. Many people fear that germline gene therapy may lead to germline enhancement, an attempt to produce a “superior” human being. Whether germline gene therapy is even needed is uncertain, because a harmful recessive trait requires mating with another human with the same trait to express itself, while dominant traits are present in only half of a germline. Identifying the sperm or egg with the normal gene and using that gene in fertilization makes more sense than trying to modify the sperm or egg with the abnormal gene. Scientists should perform genetic testing of the germline if they are to eliminate these diseases. Clearly, genetics is the current frontier in medical science. Genetics promises to prevent or cure many of the diseases that plague humans, including hereditary thyroid disease and nonhereditary tumors. But the road to those cures and preventions is full of cracks and bumps that assure a very uneven ride.

Thyroid for dummies  
Thyroid for dummies  
Advertisement