Genetic Destiny

The Brave New World of genetic profiling has arrived, in some ways unheralded. Not a paper can appear in the New England Journal of Medicine discussing a disease without an explanation of its genetic basis. Oncology, which during my decades in medicine school, until the end of the 20th century was all about using selective poisons to treat malignancies but the patients always asked the why question: Why did I get this cancer? What did I do wrong?  And the answer was, we did not know. Now we can say, well, you have this mutation in this gene and voila!  There is a tumor suppressor gene, P53, in which some people does not function properly and elephants have lots of copies of this gene and do not get any sort of malignant disease.

For all of the wonder this genetic information provides, the ability to predict and profile is even more amazing. One of my nephews recently had his genetic profile done commercially by a company called "Twenty three and Me."   What exactly they mean by a "genetic profile" I am not sure. The human genome has hundreds of thousands of genes. One gene does nothing more than guide the descent of parathyroid glands from the back of the fetal tongue down the neck to their place alongside the thyroid gland. If you have a gene with a function that discrete, can you imagine how many genes, doing how many different tasks( by making specific proteins) there must be?  How could you possibly interrogate all those genes?

Balding has long defied standard Mendelian genetics. Is it X linked?  That would make sense because balding is largely limited to men and that would mean, like color blindness, it must be on the X chromosome inherited exclusively from the mother, but there are many families in which the mother's relatives have all their hair but the father was bald and all the sons are bald, so clearly in those families the gene came from the father, not the mother.  And yet, the profile my nephew got told him he was likely to go bald, which fit the family pattern. There must be some set of genes which is known to account for this trait. 

The 23 and Me profile is also very good at placing ethnic ancestry--it identifies Jewish ancestry quite accurately, which in some circles and cultures may come as a rude shock to those who did not know of their Jewish background. 

Jews consider children born to Jewish mothers to be Jewish but not children born of gentile mothers with Jewish fathers. The rationale has long been: "You can only ever know who the mother is."  But now, you can know who the father is, and a half Jewish kid on his father's side is as genetically identifiable as  Jewish as one who is half Jewish on his mother's side.

One can imagine the mischief for all those women who presented their husbands with children fathered by a man not the husband, whose children now send off their 23 and Me sputum only to discover their biological fathers are not who they had been told they were.

I once had a patient who had got impregnated on a visit to New York City by an artist with whom she had a weekend fling,  and she was trying to decide whether she should simply have the kid and tell her husband it was his or get an abortion.   She asked my opinion and I said that would be a secret she would have to keep her whole life, and she would have to keep the lie from her child, who could never know unless she decided to tell him.  That seemed like a big burden, but she would know it was unlikely anyone but her would ever know the truth, unless the child developed some genetic disease which could not be explained by the presence of the trait in either parent.   

She decided to have an abortion, and I felt a little guilty for a long time that I did not argue more strenuously for life.  After all, given the choice between being alive and not knowing that one fact about yourself and not being alive at all, wouldn't most people choose to be alive?

I'll never know whether my musings influenced her decision much. She was the one who made the decision. But, as it turned out, the kid would now be in his thirties and he might well send off a genetic sample and she would have to explain it. Sometimes our assumptions about the inviolability of secrets prove wrong. 

In the wonderful movie, Gattaca, babies are tested with a heel stick for blood at birth and the parents are given a sort of more extensive version of the "23 and Me" in the delivery room: The life expectancy, the chances for significant heart disease, for cancer, expected levels of intelligence, athletic prowess.  Later, the news in the delivery room is supplanted by applying this to in vitro fertilization, in which the best traits the parents have to offer are selected for in the fertilization process and designer children are produced.  Children conceived in the more random way, that is by natural intercourse, and the random mingling of DNA strands are not nearly as healthy or talented as designer children and an underclass of non in vitro people develops.

Of course, as anyone who watched "The Making of a Murderer" would know, criminal investigations and "proof" of guilt is now heavily dependent on genetic analysis. The presence of a person in a place or on the body of a victim is, next to a video, the most important evidence in court. 

It all seemed pretty far fetched in 1997, when Gattaca was released. It doesn't seem quite as far fetched today.