Costello syndrome is caused by mutations in HRAS. Mutations that cause Noonan syndrome have been found in PTPN11 and SOS1.The relative severity of CFC when compared to Noonan syndrome may reflect the position in the biochemical pathway occupied by the affected genes. Shp2, the protein product of the PTPN11 gene, appears to regulate the MAP kinase pathway at or above the level of SOS1. SOS1 in turn regulates the activities of RAS, RAF, MEK, ERK, and p90RSK. SOS1 has been demonstrated to be a target of negative feedback by ERK and p90RSK.Thus, any activating mutation downstream of SOS1 may be subject to less regulation that might mitigate the consequence of such mutations, giving rise to the phenotypic differences seen between these syndromes. Diagnosis
Management
References
External links

CFC Syndrome at Genetics Home Reference
GeneReview/UW/NIH entry on CFC
Whether these concerns occur in humans is unclear. Elderly
Biophysical studies using NMR spectroscopy has provided molecular details of how inhaled anesthetics interact with three amino acid residues (G29, A30 and I31) of amyloid beta peptide and induce aggregation. This area is important as "some of the commonly used inhaled anesthetics may cause brain damage that accelerates the onset of Alzheimers disease". Physical properties
It is administered as a racemic mixture of (R)- and (S)-optical isomers. Isoflurane has a melting point of 48 - 48.5°Celsius (118 - 119°Fahrenheit) and a boiling point of 48.5 - 49 °C (119 - 120 °F). It is non-combustible but can give off irritable and toxic fumes when exposed to flame. Mechanism of action
Similar to many general anesthetics, the exact mechanism of the action has not been clearly delineated. Isoflurane reduces pain sensitivity (analgesia) and relaxes muscles. Isoflurane likely binds to GABA, glutamate and glycine receptors, but has different effects on each receptor. Isoflurane acts as a positive allosteric modulator of the GABAA receptor in electrophysiology studies of neurons and recombinant receptors. It potentiates glycine receptor activity, which decreases motor function. It inhibits receptor activity in the NMDA glutamate receptor subtypes. Isoflurane inhibits conduction in activated potassium channels. Isoflurane also affects intracellular molecules. It inhibits plasma membrane calcium ATPases (PMCAs) which affects membrane fluidity by hindering the flow of Ca2+ (calcium ions) out across the membrane, this in turn affects neuron depolarization. It binds to the D subunit of ATP synthase and NADH dehydrogenase.