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Abraham Lincoln's DNA, and Other Adventures in Genetics
by Philip R. Reilly

Reviewed by
Joel N. Shurkin

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In 1962, a Los Angeles physician diagnosed a 7-year-old boy with Marfan syndrome, a dominant genetic disorder that leads to a whole variety of complications, including early death from a ruptured heart. The patient was an indirect descendent of Abraham Lincoln (Lincoln left no direct progeny), and the physician speculated that perhaps Lincoln had the same disorder. One symptom of Marfan is unusual height; Abe Lincoln was well over six feet tall, which was highly unusual for the mid-19th century. When the gene for Marfan was discovered in 1991, an interesting question was raised: Would it be possible to obtain some DNA from Lincoln and see whether he had the disorder? After all, it would give Marfan patients some comfort to know they were in good company.

Philip Reilly, a geneticist, lawyer, and CEO of Interleukin Genetics, Inc., of Waltham, Mass., uses Lincoln's case as the title piece to his book, Abraham Lincoln's DNA, and Other Adventures in Genetics. He is an M.D. who gives courses at Harvard, Brandeis, and Tufts universities, and is president of the American Society of Law, Medicine, and Ethics, a non-profit organization in Boston. Lincoln's DNA is full of stories that provide the superstructure onto which Reilly hangs a great deal of information on one of the most important and active fields of research. Reilly calls the book a 'mini-genetics textbook,' and that it is.

Which brings us back to Lincoln.

How do you get DNA from a man more than 100 years dead when there is no chance you will be allowed to dig him up? It turns out some of the people tending the mortally wounded president had a sense of history. One young surgeon stained his shirt cuffs with Lincoln's blood. He never wore the shirt again and kept it well away from laundries. His descendants still have it. The National Museum of Health and Medicine in Washington has hair and bone fragments from the shooting. At first glance, it appeared that there would be enough material to test remnants of Lincoln's DNA for the Marfan gene.

But the tests have not been done, in part because it is not yet possible to make a definitive diagnosis with existing technology, surprising as that may seem.

There is at least one disease that mimics Marfan, and it now is clear that more than one gene is involved. We think we know that George III had porphyria, a genetic defect in the enzymes collectively responsible for making heme, the core of hemoglobin in the blood (traced as far back as Mary Queen of Scots). George III was affected sporadically, suffering from uncontrolled and irrational behavior, and was committed to asylums several times, sometimes in a straightjacket. His mental state affected his judgement and his ability to reign, and may have had a bearing on his relations with his American colonies. We know that the Hapsburgs had a protruding jaw because sometime in the 15th century one of them married a Bohemian princess with the dominant gene for that facial configurement. It ran through that family for 300 years and is obvious in family portraits.

Reilly goes through what is known about consanguineous couplings, explaining why Henri de Toulouse-Lautrec was a dwarf: His parents were first cousins. The text book part of the book is hidden in the stories—Reilly calls it a book in a book. A discussion on breast cancer can lead him into a description of somatic mutations. Particularly fascinating is the section on the use of DNA in courtrooms, especially since Reilly has often served as an expert witness. Did you know that the first man freed from prison after a DNA test had confessed to a crime he did not commit? Reilly uses those stories for an explanatory discourse on the genetic alphabet.

Reilly's sections on inheritance, personality, talent, and behavior are calm and thoughtful, even tackling such issues as the possible genetics of violence and homosexuality with considerable aplomb. He believes that the evidence for a link between genes and violent criminal behavior is strong enough to require a social debate, particularly over the legal definition of insanity.

"I think it likely that we will discover individuals with rare gene variants who are so driven to abnormal behavior that we will have to redefine the insanity defense to manage their disposition," he writes. Moreover, of course, what do you do when someone develops a test for the violent genes? And what do you do with a child with those genes?

His description of the hunt for a putative gay gene is right on the money. He points out that the famed experiments by Dean Hamer, who reported finding a gay gene, have never been completely replicated outside Hamer's lab. While it is possible that there are genetic factors contributing to male homosexuality, Reilly again questions what good that information would do—or more important, what harm would result from knowing and being able to test for gay genes. He does not take sides.

He leaves little out. From humans he moves to plants and animals and genetically altered food.

In the last third of the book, the ethicist in him comes out, but mostly to raise questions, not to answer them. First, he describes the issues over genetic testing. How do you determine who should be tested and for what? Is it better to know you carry the gene for diseases such as Huntington's? What are the ethical issues surrounding prophylactic mastectomies, or surgery to remove ovaries before cancer erupts? Should women with high risk of breast cancer undergo prophylactic surgery, he asks. The evidence that it saves lives is still somewhat ambiguous, but the genetic link with breast cancer and the BRCA1 and BRCA2 genes is undeniable.

"Imagine the difficulty of deciding whether or not to undergo prophylactic surgery," he writes. "Currently, few women request this option and few surgeons recommend it because they believe that by carefully following women at high risk they can find a breast cancer so early that it will be highly curable. On the other hand, a growing number of medical centers are offering surgery to remove the ovaries of woman who carry a deleterious BRCA1 mutation because it is not yet possible to monitor such women to catch ovarian cancer early enough to cure it."

His section on genetic therapy is a bit too calm. He brushes off the death of Jesse Gelsinger at the University of Pennsylvania and is too kind to the scientists involved. It is one of the rare times he mentions no names and finds little fault, although others have, including the Food and Drug Administration, who disciplined the scientists.

Reilly finishes with a section on eugenics. Whatever virtues there may be in breeding to quality, the foul history is inescapable and so are the questions. Reilly found that in the 1920s thousands of mildly retarded young women were sterilized by the states, but the medical records never actually recorded a sterilization procedure. You would have to believe that "20 percent or more of the young women admitted to state institutions for the mentally retarded each year needed appendectomies."

Really raises the ethical issues of what he calls the 'new negative eugenics,' using genetic testing to determine whether a pregnancy should be brought to term. Fewer families would have children with common birth defects, but with no discernible effect on the gene pool, as most of those unborn would not have reproduced anyway. It would give a new meaning to sex. And what if genetics allows people to choose the sex of their children—or their physical or mental abilities—aborting those who do not meet the new standards. "As the diagnoses of genetic disorders are made ever earlier, physicians are able to alert parents about high recurrence risks in subsequent pregnancies," he writes. "For that reason, we can expect that there will be, over time, dramatically fewer families into which a second affected child with a serious genetic disorder is born."

". Vast increases in our understanding of the role genes play in health and disease, and in our ability to acquire and process such information about the risks faced by couples, or about fetuses conceived by them, will have a frightening impact on how we think about human reproduction," he writes.

Reilly raises far more questions than he deigns to answer. He is no ideologue, which in some ways makes the book more valuable. Perhaps as a result, his book is a good place to start learning about that impact.

Joel N. Shurkin is the senior editor of HopkinsHealth in the Office of Consumer Health Information at the Johns Hopkins School of Medicine, and the author of nine books on science and the history of science.

Reilly, Philip R. Abraham Lincoln's DNA, and Other Adventures in Genetics. Cold Spring Harbor Laboratory Press, Cold Spring Harbor, NY, 2000.

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