Trilateral Project 24.1-Biotechnology 173

Generally, it is a common practice in this field of technology to clone a specific DNA, which has similar property and function to those of the DNA described in prior art, by using the hybridization method.

And the technology converting codons of amino acid by substituting any nucleotide in any position of a certain structural gene described in prior art (i.e., point mutation method) is also a common practice in this field of technology.

Therefore, in the present case, it can be readily done by using the above common practice on the basis of the prior art by a person skilled in the art to obtain a DNA encoding an "allelic mutant" with difference in just a few of amino acids.

So, inventive step would not be present in this case, in principle.

However, when the obtained specific DNA has an effect which is either qualitatively different from the that of prior art or qualitatively homogeneous but quantitatively superior, inventive step is present if a person skilled in the art cannot expect this effect on the basis of the state of the art.