In an effort to further expand its development of genetic tests for detecting cancers and infectious diseases, Abbott Laboratories plans to move a fast-growing business into larger office space in northwest suburban Des Plaines.Space allocated to Abbott Molecular will grow by more than 40 percent for its business of developing, researching and marketing genetic and DNA-based diagnostic tests by moving into the Des Plaines building, the operation’s new worldwide headquarters. The move into the former Sandoz Agro Inc. building at 1300 E. Touhy Ave. will take place before the end of the month.