Some doctors are warning that gastric bypass surgery, an extreme measure to help people lose weight, may trigger a genetic disorder that leads to genetic mutations, causing uncontrolled weight loss and death. A report in USA Today on Tuesday highlights the case of a woman, Hilary Lane, who had gastric bypass surgery in 2005, which is believed to have activated a dormant genetic mutation that derailed her metabolism, preventing her from processing proteins. Instead, her body turned protein into ammonia, which her liver could not process.
As a result of the problems following gastric bypass surgery, Lane died of urea cycle failure, weighing only 88 pounds.
Some doctors have expressed concern that other people could suffer the same fate following bypass surgery, as there have been at least six women who reportedly developed urea cycle failure since 2007, and five of them have died. In addition, this likely only represents a small fraction of such complications that have actually occurred, as most adverse events are never reported.
Gastric bypass surgery alters the size and shape of the stomach and intestines in order to address issues of extreme obesity and to promote rapid weight loss. The procedure has gained in popularity in recent years, but the changes to the body require recipients to also permanently alter the way they eat to ensure they receive the proper balance of nutrients.
The genetic disorder that killed Hilary Lane and others is called acquired urea cycle failure. In a normal urea cycle, protein metabolism creates nitrogen, which is removed from the blood stream and converted into urea, which is then removed from the body in the form of urine.
Someone suffering from acquired urea cycle failure lacks an enzyme that helps the process work. The nitrogen becomes ammonia and the ammonia cannot be processed by the liver. The ammonia is toxic and damages the body over time. In adults, it can cause what appear to be psychiatric problems, delirium, lethargy and symptoms similar to those of stroke victims. In cases where the person underwent gastric bypass surgery, it is also usually accompanied by weight loss that will not stop and cannot be controlled.
Most cases of acquired urea cycle failure are diagnosed in children because they are born with the genetic disorder already active. But some doctors say that gastric bypass surgery appears to be activating dormant genetic mutations that then cause the disorder to appear later in life.
It is unclear if the genetic disorder is activated solely by gastric bypass surgery, or by other types of bariatric weight loss surgery as well, which include the Lap-Band, duodenal switch, vertical sleeve gastrectomy and Roux-en-Y.
About 220,000 people in the U.S. underwent bariatric surgery in 2009. Gastric bypass is the most popular, and duodenal is only performed in about 1% of those operations and is reserved for the most extreme cases of obesity.