Notice of Publication of Article on Diagnostic Agent for Phenylketonuria

We address the medical challenge of declining birthrate, that is an important medical or social issue, and focus our research and development efforts on women’s and children’s diseases.

We are pleased to announce that a paper on the diagnostic agent for phenylketonuria under development has been published in the scientific journal “Molecular Genetics and Metabolism Reports”.

Wada Y, Totsune E, Mikami-Saito Y, Kikuchi A, Miyata T, Kure S. A method for phenylalanine self-monitoring using phenylalanine ammonia-lyase and a pre-existing portable ammonia detection system. Molecular Genetics and Metabolism Reports. 2023 online.

Phenylalanine is one of the amino acids that make up proteins in the body, and is converted into another amino acid called tyrosine by an enzyme. Phenylketonuria is a disease in which phenylalanine is not metabolized and accumulates in the body because the enzyme activity is congenitally low, and is designated as an intractable pediatric disease (Designated Intractable Disease 240).

The disease can cause severe symptoms such as delayed intellectual development and seizures if not treated appropriately. Mass postnatal screening was introduced in 1977, and almost all affected children have been detected at an early stage. They need to be on a dietary therapy*1 that limits phenylalanine (Phe). However, it is difficult to achieve a detailed dietary management by a test of a blood phenylalanine level at a medical institution every few months.

We have developed a system for measuring the blood phenylalanine level easily and accurately at home, in collaboration with Tohoku University. The paper published in this issue details the development and principle of this system for measuring blood phenylalanine level (“PheCheck”). Our goal is to develop a kit of this novel test system to be reimbursed by the National Health Insurance as a self-monitoring system. If the self-measurement is available at home at any time like self-monitoring of blood glucose*2 in diabetic patients, it will enable meticulous dietary management of patients with phenylketonuria.

*1 Dietary therapy

It is important to reduce the intake of phenylalanine from the diet and prevent phenylalanine accumulation. Because phenylalanine is found in protein, children with phenylketonuria should limit and refrain from eating protein foods. In addition to a low-protein diet (vegetables, potatoes, fruits, etc.), the deficient nutrients are supplemented with therapeutic milk (phenylalanine-eliminating milk).

*2 Self-monitoring of blood glucose

Diabetic patients measure their own blood glucose levels using a self-monitoring device and control their blood glucose levels by themselves. Blood glucose levels fluctuate due to various factors such as diet, exercise, medications, and physical condition, and by measuring and managing blood glucose levels themselves, they can determine when blood glucose levels are high or low. By considering the causes of high or low blood glucose levels and applying the thoughts to their own daily life and treatment, they can achieve good blood glucose control.

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