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JIMD Rep. 2019 Mar 14;46(1):28-34. doi: 10.1002/jmd2.12025. eCollection 2019 Mar.

Hyperornithinemia-hyperammonemia-homocitrullinuria syndrome in pregnancy: Considerations for management and review of the literature.

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Faculty of Arts and Science Queen's University Kingston Ontario Canada.
Department of Pediatrics, Division of Medical Genetics Kingston General Hospital Kingston Ontario Canada.
Department of Pediatrics McMaster University Hamilton Ontario Canada.
Division of Metabolics, Department of Pediatrics Children's Hospital of Eastern Ontario Ottawa Ontario Canada.
Department of Obstetrics and Gynecology Kingston General Hospital Kingston Ontario Canada.


Hyperornithinemia-hyperammonemia-homocitrullinuria (HHH) syndrome is a rare metabolic autosomal recessive urea cycle disorder. Only about 100 patients have been reported in the literature. As the population survives into reproductive years, pregnancy management becomes a new challenge for this clinicians. To our knowledge, there are less than three patients with successful pregnancies and deliveries found in the literature with no specific consensus on management or recommendations for HHH syndrome. We reviewed the current literature regarding pregnancy outcomes, combine it with our experience managing a patient through two successful pregnancies and identify a new concern of fetal intrauterine growth restriction. From this, recommendations for pregnancy management are made, including a detailed protocol for clinicians to use for disease management at delivery and in the post-partum period.


HHH syndrome; Ornithine transporter; inborn error of metabolism; intrauterine growth restriction; pregnancy; urea cycle disorder

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