Investigation of clinical and genetic characteristics of Alport syndrome using a national registry in Japan (JP-ALPS)

Yusuke Okuda¹, Naoaki Mikami², Riku Hamada², Hiroshi Hataya³, Kazuki Tanaka⁴, Chikako Terano⁴, Naoya Fujita⁴, Kenichiro Miura⁵, Kiyonobu Ishizuka⁵, Yoko Shirai⁵, Koichi Kamei⁶, Masao Ogura⁶, Takayuki Okamoto⁷, Ryota Suzuki⁷, Shunsuke Shinozuka⁸, Yuko Shima⁹, Masafumi Oka¹⁰, Wataru Shimabukuro¹¹, Hiroyasu Tsukaguchi¹², Tetsuji Inagaki¹³, Kei Nishiyama¹⁴, Taeko Hashimoto^{5

15}, Naoko Ito¹⁶, Tomohiko Yamamura¹⁷, Tomoko Horinouchi¹⁷, Kenji Ishikura¹⁸, Koichi Nakanishi¹¹, Kandai Nozu¹⁷

Affiliations

¹ Department of Pediatrics, Kitasato University School of Medicine, 1-15-1 Kitazato, Minami-ku, Sagamihara, Kanagawa, 252-0374, Japan. okuda@kitasato-u.ac.jp.
² Department of Nephrology and Rheumatology, Tokyo Metropolitan Children's Medical Center, Tokyo, Japan.
³ Department of General Pediatrics, Tokyo Metropolitan Children's Medical Center, Tokyo, Japan.
⁴ Department of Pediatric Nephrology, Aichi Children's Health and Medical Center, Aichi, Japan.
⁵ Department of Pediatric Nephrology, Tokyo Women's Medical University, Tokyo, Japan.
⁶ Division of Nephrology and Rheumatology, National Center for Child Health and Development, Tokyo, Japan.
⁷ Department of Pediatrics, Hokkaido University Graduate School of Medicine, Sapporo, Japan.
⁸ Department of Pediatrics, Matsudo City General Hospital, Matsudo, Japan.
⁹ Department of Pediatrics, Wakayama Medical University, Wakayama, Japan.
¹⁰ Department of Pediatrics, Faculty of Medicine, Saga University, Saga, Japan.
¹¹ Department of Child Health and Welfare (Pediatrics), Graduate School of Medicine, University of the Ryukyus, Ginowan, Japan.
¹² Second Department of Internal Medicine, Clinical Genetics Center, Kansai Medical University, Hirakata, Japan.
¹³ Department of Nephrology, Miyagi Children's Hospital, Sendai, Japan.
¹⁴ Departments of Pediatrics, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.
¹⁵ Yume Pediatric Clinic, Kasugai, Japan.
¹⁶ Department of Surgical Pathology, Tokyo Women's Medical University, Tokyo, Japan.
¹⁷ Department of Pediatrics, Kobe University Graduate School of Medicine, Kobe, Japan.
¹⁸ Department of Pediatrics, Kitasato University School of Medicine, 1-15-1 Kitazato, Minami-ku, Sagamihara, Kanagawa, 252-0374, Japan.

PMID: 40971131
DOI: 10.1007/s10157-025-02758-w

Investigation of clinical and genetic characteristics of Alport syndrome using a national registry in Japan (JP-ALPS)

Yusuke Okuda et al. Clin Exp Nephrol. 2025.

. 2025 Sep 19.

doi: 10.1007/s10157-025-02758-w. Online ahead of print.

Authors

Affiliations

¹ Department of Pediatrics, Kitasato University School of Medicine, 1-15-1 Kitazato, Minami-ku, Sagamihara, Kanagawa, 252-0374, Japan. okuda@kitasato-u.ac.jp.
² Department of Nephrology and Rheumatology, Tokyo Metropolitan Children's Medical Center, Tokyo, Japan.
³ Department of General Pediatrics, Tokyo Metropolitan Children's Medical Center, Tokyo, Japan.
⁴ Department of Pediatric Nephrology, Aichi Children's Health and Medical Center, Aichi, Japan.
⁵ Department of Pediatric Nephrology, Tokyo Women's Medical University, Tokyo, Japan.
⁶ Division of Nephrology and Rheumatology, National Center for Child Health and Development, Tokyo, Japan.
⁷ Department of Pediatrics, Hokkaido University Graduate School of Medicine, Sapporo, Japan.
⁸ Department of Pediatrics, Matsudo City General Hospital, Matsudo, Japan.
⁹ Department of Pediatrics, Wakayama Medical University, Wakayama, Japan.
¹⁰ Department of Pediatrics, Faculty of Medicine, Saga University, Saga, Japan.
¹¹ Department of Child Health and Welfare (Pediatrics), Graduate School of Medicine, University of the Ryukyus, Ginowan, Japan.
¹² Second Department of Internal Medicine, Clinical Genetics Center, Kansai Medical University, Hirakata, Japan.
¹³ Department of Nephrology, Miyagi Children's Hospital, Sendai, Japan.
¹⁴ Departments of Pediatrics, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.
¹⁵ Yume Pediatric Clinic, Kasugai, Japan.
¹⁶ Department of Surgical Pathology, Tokyo Women's Medical University, Tokyo, Japan.
¹⁷ Department of Pediatrics, Kobe University Graduate School of Medicine, Kobe, Japan.
¹⁸ Department of Pediatrics, Kitasato University School of Medicine, 1-15-1 Kitazato, Minami-ku, Sagamihara, Kanagawa, 252-0374, Japan.

PMID: 40971131
DOI: 10.1007/s10157-025-02758-w

Abstract

Background: Comprehensive epidemiological information regarding Alport syndrome, particularly from national cohorts, is limited.

Methods: Utilizing a national Alport syndrome cohort in Japan established in October 2022, we analyzed clinical characteristics according to genotype. Only baseline data collected retrospectively at enrollment were used. We present longitudinal trends in estimated glomerular filtration rate (eGFR) and urine protein-to-creatinine ratio.

Results: Of the 121 patients included, 105 (86.8%) underwent genetic testing and 82 (67.8%) had a kidney biopsy. Among those with genetic testing, 77 (73.3%) had X-linked Alport syndrome. Kidney function was normal at disease onset, with a median eGFR of 112.9 (interquartile range, 99.3-131.1) mL/min/1.73 m². Although a steep decline during adolescence was observed in some male patients with X-linked Alport syndrome, eGFR decline was relatively slow during childhood and adolescence; the point estimate of eGFR at age 20 was 88.6 mL/min/1.73 m². Six patients transitioned to end-stage kidney disease during the follow-up period. Eighty-one patients (66.9%) used renin-angiotensin system (RAS) inhibitors, and the rate of eGFR decline was slower after RAS inhibitor initiation. Notably, the median ages at onset and diagnosis were 3.0 and 5.1 years, respectively, because Japan's widespread urinalysis screening program for 3-year-old children enables initiation of early treatment.

Conclusions: In our cohort, which consisted mainly of patients who did not require kidney replacement therapy in childhood and adolescence, kidney function was preserved throughout this period except for some male patients with X-linked Alport syndrome. RAS inhibitor use may be associated with a reduced rate of eGFR decline.

Keywords: Alport syndrome; Registry; Renin-angiotensin system inhibitors; eGFR slope.

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Conflict of interest statement

Declarations. Conflict of interest: The Japanese Society of Paediatric Nephrology led this study. KNo is a member of advisory groups for Kyowa Kirin Co. Ltd., Toa Eiyo LTD., Zenyaku Kogyo Co. Ltd., and Taisho Pharmaceutical Co. Ltd. KNo has a patent for developing exon-skipping therapy for Alport syndrome patients. KNo receives a grant from Zenyaku Kogyo and Torii Co. Ltd. KK has received research funding from the Public Foundation of Vaccination Research Center and the Taiju Life Social Welfare Foundation; donations from Chugai Pharmaceutical, Teijin Pharma, Kyowa Kirin, Taiho Pharmaceutical, Shionogi, Daiichi Sankyo, and Mitsubishi Tanabe Pharma; lecture fees from Terumo. KNa receives consulting fees from Kyowa Kirin Co. Ltd., AstraZeneca, Kaken Pharmaceutical Co., Ltd., Ono Pharmaceutical Co. Ltd., Renalys Pharma, Inc.; research fundings from Sanofi K.K. JCR Pharmaceuticals Co. Ltd., Daiichi Sankyo Company, LTD., Chugai Pharmaceutical Co., Ltd., Astellas Pharma Inc., Asahi Kasei Corporation., Otsuka Pharmaceutical Co. Ltd., Pfizer Inc., MSD K.K., Shionogi Co. Ltd., CSL Behring; honoraria from Novartis Pharma K.K., Sanofi K.K., JCR Pharmaceuticals Co. Ltd., Taisho Toyama Pharmaceutical Co., AstraZeneca, Daiichi Sankyo Company, LTD., Teijin Pharma LTD., Chugai Pharmaceutical Co. Ltd., Miyarisan Pharmaceutical Co. Ltd., Kyowa Kirin Co. Ltd., Astellas Pharma Inc., Asahi Kasei Corporation., Ono Pharmaceutical Co. Ltd. Ethical approval: This study protocol was approved by the Institutional Review Board of Kobe University Graduate School of Medicine (B210096); the study adhered to the Declaration of Helsinki and the Ethical Guidelines for Medical and Health Research Involving Human Subjects, established by the Ministry of Health, Labour, and Welfare, Japan. In accordance with the Ethical Guidelines, the requirement for informed consent was waived in most instances; written informed consent was obtained when necessary.

References

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Investigation of clinical and genetic characteristics of Alport syndrome using a national registry in Japan (JP-ALPS)

Affiliations

Investigation of clinical and genetic characteristics of Alport syndrome using a national registry in Japan (JP-ALPS)

Authors

Affiliations

Abstract

Conflict of interest statement

References

LinkOut - more resources

Full Text Sources

Research Materials

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