Cleidocranial dysostosis (CCD), also called cleidocranial dysplasia, is a birth defect that mostly affects the bones and teeth. The collarbones are typically either poorly developed or absent, which allows the shoulders to be brought close together. The front of the skull often does not close until later, and those affected are often shorter than average. Other symptoms may include a prominent forehead, wide set eyes, abnormal teeth, and a flat nose. Symptoms vary among people; however, intelligence is typically unaffected.The condition is either inherited from a persons parents or occurs as a new mutation. It is inherited in an autosomal dominant manner. It is due to a defect in the RUNX2 gene which is involved in bone formation. Diagnosis is suspected based on symptoms and X-rays with confirmation by genetic testing. Other conditions that can produce similar symptoms include mandibuloacral dysplasia, pyknodysostosis, osteogenesis imperfecta, and Hajdu-Cheney syndrome.Treatment includes supportive measures such as a device to protect the skull and dental care. Surgery may be performed to fix certain bone abnormalities. Life expectancy is generally normal.It affects about one per million people. Males and females are equally commonly affected. Modern descriptions of the condition date to at least 1896. The term is from cleido meaning collarbone, cranial from the Greek κρανιὀς meaning skull, and dysostosis meaning formation of abnormal bone. Signs and symptoms
Cleidocranial dysostosis is a general skeletal condition so named from the collarbone (cleido-) and cranium deformities which people with it often have.
A systematic review of its use for this purpose in adult women found there was insufficient evidence of benefit and further research is needed.Methenamine acts as an over-the-counter antiperspirant due to the astringent property of formaldehyde. Histological stains
Methenamine silver stains are used for staining in histology, including the following types:

Grocotts methenamine silver stain, used widely as a screen for fungal organisms. Jones stain, a methenamine silver-Periodic acid-Schiff that stains for basement membrane, availing to view the "spiked" Glomerular basement membrane associated with membranous glomerulonephritis. Solid fuel
Together with 1,3,5-trioxane, hexamethylenetetramine is a component of hexamine fuel tablets used by campers, hobbyists, the military and relief organizations for heating camping food or military rations. It burns smokelessly, has a high energy density of 30.0 megajoules per kilogram (MJ/kg), does not liquify while burning, and leaves no ashes, although its fumes are toxic. Standardized 0.149 g tablets of methenamine (hexamine) are used by fire-protection laboratories as a clean and reproducible fire source to test the flammability of carpets and rugs. Food additive
Hexamethylene tetramine or hexamine is also used as a food additive as a preservative (INS number 239). It is approved for usage for this purpose in the EU, where it is listed under E number E239, however it is not approved in the USA, Russia, Australia, or New Zealand. Reagent in organic chemistry
Hexamethylenetetramine is a versatile reagent in organic synthesis.