1. A mere DNA fragment without indication of a function or specific asserted utility is not a patentable invention.
2. A DNA fragment, of which specific utility, e.g. use as a probe to diagnose a specific disease, is disclosed, is a patentable invention as long as there is no other reasons for rejection.
3. A DNA fragment showing no unexpected effect, obtained by conventional method, which is assumed to be part of a certain structural gene based on its high homology with a known DNA encoding protein with a known function, is not a patentable invention. (EPO, JPO). The above-mentioned DNA fragment is unpatentable if the specification fails to indicate an asserted utility. (USPTO)
4. The mere fact that DNA fragments are derived from the same source is not sufficient to meet the requirement for unity of invention.