How Much DNA Is Too Much? (Brief Constructed Response)?

So clearly the prompt wants you to talk about genetic diseases. As the prompt mentions most diseases are recessive. Therefore every allele must express that disease in order for that organism to have that disease; otherwise it is merely a carrier. This reason is oftentimes why men are new suceptable to sex-related disease than men. A man only has one x chromosome. If the disease is in the x chromosome a man only has one x chromosome and must express the gene from that chromosome and therefore the Disease. Women have a choice. If only one chromosome has the gene then only half the cells will express the disease, usually not enough to visibly effect her. The more copies of a Gene the less likely that all of those genes will express the gene and therefore the organism will be heterozygous for that trait and will not express it. However I would also mention that if a disease is dominant it will be more likely that an organism with more chromosomes will get that disease. Also DNA replication is difficult and energy intensive. The more copies of a gene means that more energy is required and there is a greater potential for error in the coding. This could slow growth and increase the mutation rate. Thats just what I thought was relevant off to top of my head. Hope that helps.