Design and assembly of the computational gene exemplified with one eukaryotic gene. A) Diagnosis. The 24 nt long double-stranded diagnostic duplex Am/AB' bears three mismatches positioned at the centre. The single-strand Am represents the mutation signal and the AB' strand the diagnostic signal. The displacement of AB' from Am is thermodynamically favourable due to the full complementary of Am' to Am. Regions highlighted in bold show the positions where mismatches were located before strand displacement. B) Therapy. The eukaryotic hID1 gene is the skeleton of the computational gene. The conserved regions of hID1 serve as constants for designing a functional gene being (for simplicity and demonstration purposes) a part of the hID1 gene product itself. For this reason, the intron sequence of hID1 was modified to construct the required initial and final accepting states, keeping the conserved splicing signals intact. The three elements, e.g., initial state (part A), diagnostic signal (AB'), and final state (part B), revealed a functional 1.6 kb gene encoding a 155 amino acid long (17.3 kDa) protein.