Zone in with Zon—mtDNA, Inherited Disease, and Designer Babies

Dr. Gerald Zon’s latest “Zone in with Zon” blog post, dated August 4, 2014, and published by TriLink BioTechnologies of San Diego, discusses the topic of mitochondrial DNA (mtDNA) replacement in the context of eliminating disease and creating designer babies. Dr. Zon begins by giving some background on mtDNA and disease, together with a description of TriiLink’s connection with mtDNA. Initially, Dr. Zon notes that TriLink has recently introduced mtDNA PCR sequencing primers (mitoPrimers™) and an mtDNA amplification kit (mitoKit™) for forensic science and casework. Then, Dr. Zon notes that given the relatively small amount of mtDNA (~16,569 base pairs and 37 genes) in a human mitochondrion compared to genomic DNA (~2 billion base pairs and ~20,000 genes) in a human nucleus, the list of mtDNA diseases is quite lengthy. Dr. Zon notes that approximately one in 4,000 babies in the U.S. is born with an inherited mitochondrial disease. There is no known treatment for these diseases and few of the afflicted children grow into adulthood. Dr. Zon describes a recent New York Times article on Dr. Shoukhrat Mitalipov, of Oregon Health and Science University, who has developed a procedure to help women conceive children without passing on their mtDNA defects. Dr. Mitalipov’s procedure would allow these women with mtDNA mutations to bear children by placing the nucleus from the mother’s egg into a donor egg whose nucleus has been removed. The defective mitochondria, which float outside the nucleus in the egg’s cytoplasm, are left behind, thus eliminating the possibility of passing along defective mitochondria. Dr. Zon pointed out that while some advocate this process because it eliminates a significant problem, others are skeptical as the child would bear the genes of three parents—mother, father, and donor—posing a possible ethical dilemma.