H5N1 genetic structure is the molecular structure of the H5N1 virus's RNA. H5N1 is an Influenza A virus subtype. Experts believe it might mutate into a form that transmits easily from person to person. If such a mutation occurs, it might remain an H5N1 subtype or could shift subtypes as did H2N2 when it evolved into the Hong Kong Flu strain of H3N2. Genotype Z of H5N1 is now the dominant genotype of H5N1. Genotype Z is endemic in birds in southeast Asia and represents a long term pandemic threat. Influenza A viruses have 11 genes on eight separate RNA molecules Orthomyxoviruses: