What does PAC stand for?

Formidable technical obstacles remain, but some designer-baby advocates are convinced that solutions are in view. Many pin their hopes on the development of human artificial chromosomes (HACs). These synthetic "microchromosomes" are "assembled from individually isolated components of naturally occurring chromosomes. " Geneticists believe that HACs may overcome the delivery problems and the limited capacity of viral vectors, allowing them both to avoid interfering with natural chromosomes, and to put into one package the multiple genes that would be needed to produce most traits.