Recent studies in two individuals with PKS found their sSMCs consisted specifically of genetic material located in a stretch of chromosome 12 s p arm starting at its band 11 and running to its end. This area, called the PKS critical region, contains three genes, ING4, CHD4, and MFAP5 (also termed the MAGP2 gene), which are candidates for contributing to the development of the syndrome.One suggested mechanism for the development of the sSMC in PKS involves three sequential events: 1) chromosome 12 suffers a nondisjunction, i.e. a failure of its homologous chromosomes or sister chromatids to separate properly during the second meiosis cell division that forms maternal eggs; 2) while most of the eggs with this nondisjunction die, a rare egg with the nondisjunction acquires a second structural aberration, isochromosome formation, that results in the creation of an extra chromosome consisting of copies of two or four p arms but no q arms of chromosome 12, i.e. the sSMC; and 3) the sSMC-containing egg, after being fertilized by a genetically normal sperm, develops into an offspring containing copies of this sSMC in some but not all cells, tissues, and/or organs consequently have some but not all of the defects associated with PKS. This mechanism applies only to female parents who are by far the most common originators of the sSMC in PKS. The mechanism explaining the few cases in which male parents form a sperm containing this sSMC has not yet been clearly formulated.
Dexlansoprazole, sold under the trade names Dexilant and Biozodex among others, is a medication which reduces stomach acid. It is used to treat gastroesophageal reflux disease. Effectiveness is similar to other proton pump inhibitors (PPIs). It is taken by mouth.Common side effects include diarrhea, abdominal pain, and nausea. Serious side effects may include osteoporosis, low blood magnesium, Clostridium difficile infection, anaphylaxis, and pneumonia. Use in pregnancy and breastfeeding is of unclear safety. It works by blocking H+/K+-ATPase in the parietal cells of the stomach.Dexlansoprazole was approved for medical use in the United States in 2009. In Canada in 2016, it was the most expensive PPI available. In 2019, it was the 218th most commonly prescribed medication in the United States, with more than 2 million prescriptions. Medical use
Dexlansoprazole is used to heal and maintain healing of erosive esophagitis and to treat heartburn associated with gastroesophageal reflux disease (GERD). It lasts longer than lansoprazole, to which it is chemically related, and needs to be taken less often. There is no good evidence that it works better than other PPIs. Adverse effects
The most significant adverse reactions (≥2%) reported in clinical trials were diarrhea, abdominal pain, bloating, nausea, upper respiratory tract infection, vomiting, and flatulence. Mechanism of action
Like lansoprazole, dexlansoprazole permanently binds to the proton pump and blocks it, preventing the formation of gastric acid. Chemistry
Dexlansoprazole is the (R)-(+)-enantiomer of lansoprazole, which is a racemic mixture of its (R)-(+) and (S)-(−)-enantiomers.