# How to Design Effective siRNA Molecules to Silence Specific Genes > A patent detailing the precise chemical structure and sequence requirements for siRNA molecules designed to effectively turn off the AAT gene in cells. - **Patent:** US 9839649 - **Original title:** Methods and compositions for selecting siRNA of improved functionality - **Owner:** Thermo Fisher Scientific Inc - **Granted:** 2017 - **Status:** Active - **Times cited:** 3 - **Field:** biotech, pharmaceutical ## What it does This patent describes the structural requirements for small interfering RNA (siRNA) molecules used to trigger gene silencing. It specifies that the molecule must consist of a sense and antisense strand, each between 19 and 30 nucleotides long, forming a duplex region. Crucially, the antisense strand must be a complement to a specific target sequence identified as SEQ ID NO:465, which corresponds to the AAT gene. The patent allows for variations in the presence or absence of short nucleotide overhangs at the ends of the duplex. ## What it does NOT cover - Does not cover siRNA molecules that target genes other than the AAT gene specified by SEQ ID NO:465. - Does not cover RNA molecules longer than 30 nucleotides. - Does not cover single-stranded RNA molecules. - Does not cover methods of delivering these molecules into a living organism. ## The clever bit The innovation lies in the rational design criteria: by strictly defining the length (19-30 nucleotides) and the exact sequence complement required for the antisense strand, the inventors ensure the siRNA molecule is optimized for the cell's natural silencing machinery, minimizing off-target effects. ## Real-world examples 1. RNA interference research tools 2. Experimental gene silencing therapies for Alpha-1 Antitrypsin deficiency ## Why it matters This patent is significant for the field of RNA interference (RNAi), a biological process where RNA molecules inhibit gene expression. By defining the exact sequence and structural parameters for targeting the AAT gene—often associated with Alpha-1 Antitrypsin deficiency—it provides a blueprint for developing therapeutic reagents that can precisely 'switch off' disease-causing genes. ## Frequently asked questions ### What does How to Design Effective siRNA Molecules to Silence Specific Genes cover? A patent detailing the precise chemical structure and sequence requirements for siRNA molecules designed to effectively turn off the AAT gene in cells. ### Who owns patent US 9839649? Thermo Fisher Scientific Inc owns this patent, granted in 2017. ### When does this patent expire? This patent is expected to expire on November 9, 2035, when the invention enters the public domain. ### What is patent US 9839649 cited by? This patent has been cited by 3 later patents that build on its ideas. ### What problem does this patent solve? This patent is significant for the field of RNA interference (RNAi), a biological process where RNA molecules inhibit gene expression. By defining the exact sequence and structural parameters for targeting the AAT gene—often associated with Alpha-1 Antitrypsin deficiency—it provides a blueprint for developing therapeutic reagents that can precisely 'switch off' disease-causing genes. ### What does this patent NOT cover? Does not cover siRNA molecules that target genes other than the AAT gene specified by SEQ ID NO:465. **Full plain-English explainer:** https://patentbrief.org/patent/us/9839649/methods-and-compositions-for-selecting-sirna-of-improved-functionality **Original patent:** https://patents.google.com/patent/US9839649 --- _Source: PatentBrief — https://patentbrief.org. Patent facts are from public records; the plain-English explanation is PatentBrief's._ ## Related patents Semantically similar inventions in the PatentBrief corpus: - [How Modified RNA Tricks Cells Into Making Proteins Without Triggering Attacks](https://patentbrief.org/patent/us/8278036/rna-containing-modified-nucleosides-and-methods-of-use-thereof) — A breakthrough method for using modified RNA to deliver instructions to cells without causing the body to reject the treatment as a foreign invader. - [How to Edit Genes in Human Cells Using an Engineered CRISPR System](https://patentbrief.org/patent/us/8697359/crispr-gene-editing) — This patent describes an engineered CRISPR-Cas9 system for precisely cutting DNA in eukaryotic cells to change how genes work, opening the door for gene editing in complex organisms. - [How CRISPR-Cas9 Uses RNA to Edit DNA](https://patentbrief.org/patent/us/10113167/methods-and-compositions-for-rna-directed-target-dna-modification-and-for-rna-directed-modulation-of-transcription) — This patent describes the fundamental mechanism of using a two-part RNA system to guide the Cas9 protein to specific locations in DNA for precise editing. - [How Synthetic Peptides Block Immune System Overreaction](https://patentbrief.org/patent/us/10106579/orkambi-lumacaftor-ivacaftor) — A patent describing specific synthetic peptides designed to stop the body's immune system from attacking healthy cells by blocking a protein called C5. - [Chemical Compounds for Treating Hepatitis C Virus](https://patentbrief.org/patent/us/8822430/epclusa-sofosbuvir-velpatasvir) — A patent describing specific chemical structures designed to stop the Hepatitis C virus from replicating in humans.