Earlier this year, a Chinese scientist reported the birth of twin girls whose genomes had been modified to silence the CCR5 gene. The birth was reported to be one of a series of human embryo experiments designed to render the offspring resistant to infection by HIV.
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Most scientists have applied the CRISPR/Cas system to specific tissues or to stem cells. Bedford Research scientists are applying the technology to edit B2M gene sequences in unfertilized eggs which are subsequently activated for stem cell derivation. Last year a Portland Oregon research team reported their efforts to repair a mutation in the gene MYBPC3 known to be associated with acute heart failure in young men.
Early gene editing experiments were accomplished by mating individuals with different traits. Two well known examples are Mendel’s famous red peas crossed to white peas to yield pink peas and Mr. Little’s Fancy Mice, bred for coat color, formed the basis of the Jackson Laboratory’s inbred mice to study genetic diseases.
No two individuals have exactly the same gene sequences because multiple sequences code for the same amino acid. This is the basis for DNA tests to prove paternity or predict ancestry. Most of the gene variations do not change the proteins they code for, but some do, such as genes for eye and hair color and height.
Is gene editing human embryos a positive scientific breakthrough for human health, or misuse of a powerful research tool? Over the next six months, we will outline the basic biology behind gene editing, followed by a description of the process in general and in human embryos, specifically.