Matthew Klein, MD, MS, FACS, Chief Development Officer at PTC Therapeutics, provides an overview of phenylketonuria (PKU).

As Dr. Klein explains, PKU is a rare genetic metabolic disorder caused by a defect in the gene involved in the production of phenylalanine hydroxylase, an enzyme needed to break down the amino acid phenylalanine. The accumulation of phenylalanine can cause damage multiple organs, most notably the central nervous system. If PKU is left untreated, patients can develop chronic intellectual, neurodevelopmental, and psychiatric disabilities, as well as seizures and heart problems. 

Lifelong restriction of phenylalanine intake through the diet is needed to prevent buildup of phenylalanine in the body. However, this diet, as Dr. Klein notes, is particularly difficult to stick to. This has motivated many pharmaceutical companies, such as PTC Therapeutics, to develop a targeted therapy. 

The disease affects 1 in 12,000 babies in the U.S, and affects males and females equally. It is also part of many newborn screening programs, which leads to early diet intervention that can reduce damage caused by the disease.

To learn more about PKU and other rare metabolic disorders, visit