Type XIX – OI caused by hemizygous mutation in the MBTPS2 gene on chromosome Xp22.12. Thus far, OI type XIX is the only known type of OI with an X-linked recessive pattern of inheritance, making it the only type that is more common in males than females. OI type XIX disrupts regulated intramembrane proteolysis, which is critical for healthy bone formation. Type XX – OI caused by homozygous mutation in the MESD gene on chromosome 15q25.1. Initial studies of type XX indicate that it may cause global developmental delay, a first among OI types. OI type XX disrupts the Wnt signaling pathway, which is thought to have a role in bone development. Type XXI – OI caused by homozygous mutation in the KDELR2 gene on chromosome 7p22.1. Causes disease clinically similar to types II and III, thought to be related to inability of chaperone protein HP47 to unbind from collagen type I, as to do so it needs to bind to the missing ER lumen protein retaining receptor 2 protein encoded by KDELR2.Given the rapid rate of type discovery, it is extremely likely that there are other genes associated with OI that have yet to be reported. : 491–492

Genetics
Osteogenesis imperfecta is a group of genetic disorders, all of which cause bone fragility.
In 1998, a small pharmacokinetic (PK) study failed to show that differences in a patients ability to clear naproxen from the body could account for differences in a patients risk of experiencing the adverse effect of a serious gastrointestinal bleed while taking naproxen. However, the study failed to account for differences in the activity of CYP2C9, a drug-metabolizing enzyme that is necessary for clearing naproxen. Studies on the relationship between CYP2C9 genotype and NSAID-induced gastrointestinal bleeds have shown that genetic variants in CYP2C9 that reduce the clearance of major CYP2C9 substrates (like naproxen) increase the risk of NSAID-induced gastrointestinal bleeds, especially for homozygous defective variants. Chemistry
Naproxen is a member of the 2-arylpropionic acid (profen) family of NSAIDs. The free acid is an odorless, white to off-white crystalline substance. It is lipid-soluble and practically insoluble in water. It has a melting point of 152–155 °C. Synthesis
Naproxen has been industrially produced by Syntex starting from 2-naphthol as follows:

Society and culture
Brand names
Naproxen and naproxen sodium are marketed under various brand names, including Accord, Aleve, Anaprox, Antalgin, Apranax, Feminax Ultra, Flanax, Inza, Maxidol, Nalgesin, Naposin, Naprelan, Naprogesic, Naprosyn, Narocin, Pronaxen, Proxen, and Soproxen. It is also available as the combination naproxen/esomeprazole magnesium in delayed release tablets under the brand name Vimovo. Access restrictions
Syntex first marketed naproxen in 1976, as the prescription drug Naprosyn. They first marketed naproxen sodium under the brand name Anaprox in 1980. It remains a prescription-only drug in much of the world.