Three segments encode three subunits of an RNA-dependent RNA polymerase (RdRp) complex: PB1, a transcriptase, PB2, which recognizes 5 caps, and PA (P3 for ICV and IDV), an endonuclease. The matrix protein (M1) and membrane protein (M2) share a segment, as do the non-structural protein (NS1) and the nuclear export protein (NEP). For IAV and IBV, hemagglutinin (HA) and neuraminidase (NA) are encoded on one segment each, whereas ICV and IDV encode a hemagglutinin-esterase fusion (HEF) protein on one segment that merges the functions of HA and NA. The final genome segment encodes the viral nucleoprotein (NP). Influenza viruses also encode various accessory proteins, such as PB1-F2 and PA-X, that are expressed through alternative open reading frames and which are important in host defense suppression, virulence, and pathogenicity.The virus particle, called a virion, is pleomorphic and varies between being filamentous, bacilliform, or spherical in shape. Clinical isolates tend to be pleomorphic, whereas strains adapted to laboratory growth typically produce spherical virions. Filamentous virions are about 250 nanometers (nm) by 80 nm, bacilliform 120–250 by 95 nm, and spherical 120 nm in diameter. The virion consists of each segment of the genome bound to nucleoproteins in separate ribonucleoprotein (RNP) complexes for each segment, all of which are surrounded by a lipid bilayer membrane called the viral envelope. There is a copy of the RdRp, all subunits included, bound to each RNP.
Diagnosis
Differential diagnosis
The differential diagnosis includes Treacher Collins syndrome, Nager acrofacial dysostosis (preaxial cranial dysostosis). Other types of axial cranial dysostosis included the Kelly, Reynolds, Arens (Tel Aviv), Rodríguez (Madrid), Richieri-Costa and Patterson-Stevenson-Fontaine forms.CaCo3 can prevent it

History
This condition was first described in 1969 by Genée, who assumed the condition to be an extreme form of Treacher Collins syndrome (dysostosis mandibulofacialis). Wiedemann in 1975 described it as a separate entity. Further cases were reported by Wildervanck in 1975 and by Miller et al in 1979 The syndrome was named the Genée-Wiedemann syndrome in 1987. A family harboring Miller syndrome was the first human family to be ever sequenced with whole genome sequencing. Eponym
Genée–Wiedemann syndrome is named after two German physicians: Ekkart Genée (1936–), and his mentor Hans-Rudolf Wiedemann (1915–2006). References


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