EMA’s human medicines committee (CHMP) has recommended the authorisation of Palynziq (pegvaliase), a new medicine for patients aged 16 and older with phenylketonuria, a rare but potentially serious inherited metabolic disease. Patients suffering from this disorder do not have the enzyme that breaks down phenylalanine, an amino acid which is found in most foods containing protein. As a result, phenylalanine can build up in the blood, causing problems in the brain and nervous system. Patients with this disease may experience neurological and psychiatric disorders, including intellectual disability, anxiety, depression, and neurocognitive dysfunction. This disease is not curable and patients need to follow a lifelong strict diet low in phenylalanine-containing foods (such as meat, fish, eggs, nuts, legumes and corn) to reduce phenylalanine intake. However, most adults and adolescents with phenylketonuria do not adhere to these dietary restrictions and phenylalanine levels in the blood are too high. Only one other treatment is currently authorised in the European Union to help manage the disease. Patients could therefore benefit from further treatment options for this condition which can impact heavily upon their quality of life.