Chimeras - everyone and no one

“As a net is made up of a series of ties, so everything in this world is connected by a series of ties. If anyone thinks that the mesh of a net is an independent, isolated thing, he is mistaken.”

- Buddha

Microchimerism is the existence of a low concentration of genetically distinct cells within a person. Macrochimerism is the same, but the concentration of genetically distinct cells is greater (upward of 2.5%) and said cells may comprise an entire organ of the body, such as the gonads.

It is caused by pregnancy (wherein there is a transfer of cells between: the mother and child, no matter whether the baby miscarries, is terminated or is born; and between residual cells of an older sibling and the child), twinning (where one twin is absorbed by the other twin in the uterus), unprotected sex, blood transfusions, and organ transplants. As a consequence, virtually everyone is at least microchimeric, possibly with several different types of genetically distinct cells within them. (It is ironic then that, in 2005, the Human Chimera Prohibition Bill was introduced before Congress. It was not passed. If it had been, it would have created an awkward scenario in which seemingly every single person would be in violation.)

This poses a number of practical and legal issues.

From a practical standpoint, how is one supposed to artfully pick a mate? Attraction is at some level a consequence of one's compatibility with another's immunity profile (and, in association, with their genetic profile). This is communicated subconsciously via pheromones and consciously by one's observable phenotype. So, if we carefully read these genetic cues and select a mate that has a genetic profile that complements (and would seemingly combine with) our own to produce the best possible offspring, aren't we then severely duped if the mate we chose turns out to be macrochimeric and the genetic material s/he contributes to the offspring is completely different to the genetic material we observed and selected?

From a legal perspective, some of the problems have already been pondered. The most oft raised problem being: what if we clear rapists because we test their DNA from a blood sample and that DNA does not match the semen DNA found on the victim, but then it turns out that they are incorrectly cleared because, in truth, they are the perpetrator but they are just macrochimeric, so that their blood cell DNA is entirely different to their semen cell DNA? Do we need to start asking those accused of rape to provide semen samples rather than blood samples? This might be the only way to ensure that perpetrators are not accidentally vindicated. However, requiring someone to masturbate in order to produce a semen sample, would seem to amount to an affront to the accused's human rights.

But the objective of this blog has always been to canvass issues that, to my knowledge, are yet to have been conceptualized and addressed. Thus, I will rather focus on a legal problem that revolves around a legal consequence of chimerism that is yet to have been pondered, namely the ability to provide informed consent for the use of, and the ability to claim intellectual property rights in, one's DNA when one is in fact comprised of many genetically distinct cells, including: the cells of one's mother's, and the cells of one or more of one's lover(s), older siblings and children.

Do we have the right to give informed consent for the use of any of our cells, and to claim IP rights in any of our cells, or only our primary DNA cells (i.e. not the small percentage of chimeric cells)?

Let me preface the ensuing discussion with the acknowledgement that the case of Moore v Regents of the University of California established that consent to an operation to have tissue removed entails an abandonment of any claims over the removed tissue. Thus, Moore had no IP rights in his hairy cell leukemia cells after they had been removed by Goode (a doctor employed by the University of California). But, it is my contention that this is not the end of the story. Bioethicists still argue that patients should be offered compensation for their donation of waste tissue by a fixed fee or a chance to share in the rewards of financially successful research. This discussion in set to heat in the wake of the worldwide spate of Myriad Genetics cases, regarding the patentability of gene sequences. So, the ensuing discussion is based on the assumption that, at some point, the law could be modified such that people will be entitled to compensation for their DNA.

With this disclaimer, I continue...

Henrietta Lacks died of cervical cancer in the 1950's. Without her knowledge or consent, her cervical cancer cells (dubbed HeLa cells) were taken and reproduced in a laboratory, to amass numbers sufficient enough for sale and worldwide experimentation (resulting in huge financial gains for all concerned, except Henrietta or her descendents). In theory, this should not occur today, as doctors are now required to get informed consent before taking and experimenting on cell samples. But, in reality, the same exact outcome could occur if someone gave informed consent for the use of their chimeric cells for experimentation, but the person who is principally comprised of those cells (either the offspring, or the mother, or the organ donor etc) has not consented. In such a case, just as Henrietta Lacks (or her children, after her death) had no control over the use of her DNA for experimentation, the person who is principally comprised of the chimeric cells, would have no control over the use of their DNA.

This has been an issue with regard to identical twins (that have near identical DNA). As it stands, one twin can consent to the provision of a cell sample, which means the identical twin is subjected to the consequences even though he/she may not have agreed with the provision of consent. These consequences include privacy issues with respect to the revelation of the twin's DNA profile, psychological issues with respect to (as happened with Henrietta Lack's offspring) the emotional trauma of envisioning their mother's cells becoming immortal and being blown up or otherwise subject to experimentation, and the financial issues of remuneration.

Previous complexities in the issues of consent and compensation as they applied to identical twins are now far more wide reaching. If it is not just identical twins that share cells of near identical DNA, but virtually all of us who do, then the problem of obtaining consent and compensating rightful parties escalates.

It cannot be that consent can only be provided, and rights claimed in, the primary DNA cells as this is incongruous with both precedence and reality. When cancerous cells are taken for experimentation, the DNA of those cells has mutated such that the cancerous cells differ from the primary DNA cells of the person. Despite this, it has never been argued that, because the cancerous cells are genetically distinct from the primary DNA cells of the person, that person cannot provide consent for the use and experimentation of the cancerous cells. How could this be argued? Practically, those cancerous cells comprise part of the person and so are his/hers over which to provide consent. Equally, it would be very difficult to limit a person's right to give consent to (and potentially claim intellectual property rights in) their chimeric cells. After all, those cells comprise part of the person.

Thus, it seems the only answer is for us to acknowledge our interconnectedness, and construct the law in such a way as to respect people's rights to privacy, self determination and compensation as best as possible.