It is with profound sadness that we received the news of the passing of Dr. Yoshiyuki Okano on Oct 26, 2021. We are fortunate to have crossed path with him, experiencing firsthand his unwavering dedication and kindness. It has been our great honor to have known and worked with him. He was a selfless doctor, an honorable man, and a precious friend.   

Dr. Okano was always a doctor at heart. In every conversation with him, you could feel his passion to medicine and devotion to the wellbeing of his patients. His concern for the patients extended far beyond his clinic, into the global community of citrin deficiency (CD) patients. His care for his patients was also holistic, as he understood that for a rare disease that is not completely understood, we needed to pay attention to the quality of life and emotional wellbeing of the patients. This compelled him to conduct the first ever QOL study for CD patients ‘Fatigue and quality of life in citrin deficiency during adaptation and compensation stage‘, published in 2013. When he was working as a lecturer and pediatric clinician at Osaka City University, he authored and published many papers on CD. Even after setting up his private clinic in 2011, he continued his involvement in the research on CD. He continued to attend the annual Patient Association meeting, where besides often being a presenter of his latest findings, he was always an active participant in the patient discussion groups. He listened attentively to the concerns of the patients and addressed them with the utmost seriousness and compassion. His advice to the patients was always illuminating, empathetic, and reassuring. He was unquestionably a source of comfort and wisdom for all the patients he encountered. Watching him interacting with the patients leaves no doubt what a wonderful doctor he was.

Dr. Okano was also a great family man. We had the pleasure of meeting his wonderful family, his wife Noriko, and his daughter Mai multiple times. Mai, inspired by her father, has followed in his footsteps and become a pediatrician. Our deepest condolences to Noriko and Mai. Dr. Okano will be dearly remembered by us.

Dr. Okano had been involved in the research and treatment of CD for decades, making him one of the few pediatric researchers/clinicians in this field. His expertise encompassed a broad spectrum, with a particular focus on therapeutics such as sodium pyruvate and diet intervention. The Citrin Foundation started funding his study in 2017 to construct guidelines of treatment of CD. When we discussed with Dr. Okano of the lack of published treatment guidelines on CD, he gladly took on the responsibility as he knew how important it was to have proper treatment guidelines on CD for doctors around the world. He published the paper titled ‘Current treatment for citrin deficiency during NICCD and adaptation/compensation stages: Strategy to prevent CTLN2’  in Molecular Genetics and Metabolism in 2019.

His dedication to helping patients spurred him to conduct a new study to update the previous understanding of the diet and quality of life of CD patients. With the support of the Foundation, he conducted a detailed survey on the food preference and quality of life of patients in Japan. Thanks to the cooperation from many doctors, institutions, the patient association, and the patients themselves, the survey received a great response. He completed and published the paper titled ‘Analysis of daily energy, protein, fat, and carbohydrate intake in citrin-deficient patients: Towards prevention of adult-onset type II citrullinemia’  in March 2021 in Molecular Genetics and Metabolism.

While conducting the diet survey, Dr. Okano received many interesting comments from patients on their diet. In response to their comments, he conducted an additional survey and started engaging Miki Okamoto — a dietitian who worked closely with him in his clinic — on a new paper. During the process he went through painful, long, and repeated treatments to battle his illness, but he was not deterred to finish his work. He worked tirelessly from morning till night, seven days a week to complete the paper. The fruit of his hard work, ‘Food Preferences of Patients with Citrin Deficiency’, was published in Nutrients in September 2021. His dedication was truly admirable.

Our last meeting with Dr. Okano was a global Zoom conference attended by all our Principal Investigators and their team members. Dr. Okano was already in the late stage of his illness and had undergone multiple exhausting treatments, and yet he insisted on attending the hours long conference. His tireless spirit and dedication moved us deeply and will always be our lasting memory of him. We are eternally grateful to him, and he will be greatly missed. May he rest in peace.