No More Genetic Heart Defects?
If you had a known genetic predisposition to a deadly disease or condition, would you take advantage of technology to remove the DNA which causes the disease in your offspring? Even if it meant you could not procreate the “natural” way but would need to have in vitro fertilization? Is the thought of this kind of genetic editing too Brave New World for mainstream medicine?
Recently, researchers at the Oregon Health and Science University used CRISPR technology to identify and remove the gene which causes hypertrophic cardiomyopathy (HCM) from an embryo created specifically for this study (not implanted). HCM is a genetic heart condition which causes a thickening of the heart muscles and is one of the leading causes of sudden cardiac arrest in young athletes. It is thought one in every 500 people in the US have this condition, but most have no symptoms or mild symptoms are wrongly attributed to other conditions. For those who do have it, however, they are literally a ticking time bomb and can suffer sudden cardiac arrest at any time. Do we owe it to future generations to eradicate this condition completely?
The most impressive aspect of this accomplishment is it involves germline DNA, defined by the NCI Dictionary of Genetics Terms as “tissue derived from reproductive cells (egg or sperm) that become incorporated into the DNA of every cell in the body of the offspring. A germline mutation may be passed from parent to offspring.” In a nutshell, this means if a bad mutation is corrected or removed at the time of fertilization, it can no longer be passed along to direct descendants. Understanding this is possible gets the “what if” machine rolling and more questions than answers are available right now. What if there were no more inherited cancers like breast, colorectal, prostate, or ovarian? Why stop at cancer? What if we could also eliminate other single-gene diseases like cystic fibrosis, sickle cell anemia, Huntington’s, or Marfan’s?
While the thought of reducing human suffering should only be positive, some have claimed this same technology opens up the possibility for creating ‘designer babies’. It is important to note in this study CRISPR was not used to enhance a DNA strand with the goal of creating desirable attributes like hair and eye color, athletic ability, or IQ (all of which have been discovered to involve a complex combination of genes), but instead was used to correct a DNA strand by removing a defective gene from a male donor’s sperm so as the embryo developed it could correct for the missing gene and repair itself using the healthy mother’s genetic material.
Of course, the hope is we can correct for genetic defects either in the womb or after the child is born, ensuring the gene never gets “turned on” during the person’s lifetime. If DNA testing were done to determine what genes a person has which cause everything from ALS to male pattern baldness, a future solution may be a one-time treatment to knock out all the ‘bad’ or undesirable (from a medical standpoint) genes. It could be a literal silver bullet for disease. What the future holds for the possible applications of this technology is mind-boggling.