Ultra-high-throughput DNA sequencing has helped researchers to discover a heretofore unknown inherited form of human obesity and type 2 diabetes.1 Though it's unclear what proportion of these disorders are caused by genetic disease, it is known that more than 30 genes are susceptible to DNA changes that cause extreme overweight; and similarly, genes can be altered to cause type 2 diabetes.
Using Illumina's HiSeq25000, the team, from Imperial College London, sequenced the DNA of a woman with extreme obesity and diabetes. They found that she had inherited two copies of a genetic change that prevents her from making carboxypeptidase-E (CPE)—an enzyme important for processing of hormones and brain transmitters that control appetite, insulin, and more.
CPE deficiency has been known to cause obesity, diabetes, and memory impairment in mice, but no humans with the condition had previously been found. Alex Blakemore, a professor in the Department of Medicine at Imperial College, who led the study, notes that such tests should be widely available. "Diagnosis is very valuable to the patient. It helps to set realistic expectations, and can help them get the best possible treatment," she says. It can also make available genetic advice to family members who want it.
1. S. I. M. Alsters et al., PLoS One (2015); doi:10.1371/journal.pone.0131417.
