Humans, Chimps not as closely related as thought?

For a long time scientists used DNA from humans and chimps and was closely related in genetic material. Several studies showed of how these two species could be so close in DNA. When they did a study of human and mice they werent close in percentage as a chimp. DNA proves that humans and chimps are closely related to each other, but not the gorilla. Even though they are quite compariable. Humans catch more diseases compared to the chimp.