Surreal illustration of sugar molecules within a child's silhouette, symbolizing Fructose-1,6-bisphosphatase Deficiency.

Fructose-1,6-bisphosphatase Deficiency: What Parents Need to Know

Lena Voss in Health & Wellness December 2025 • 4 min read.

"Early diagnosis through genetic testing can help manage this rare metabolic disorder and prevent serious complications."

Fructose-1,6-bisphosphatase (FBPase) deficiency is a rare, inherited metabolic disorder that disrupts the body's ability to produce glucose from non-carbohydrate sources, a process known as gluconeogenesis. This condition can lead to episodes of low blood sugar (hypoglycemia) accompanied by metabolic and lactic acidosis, which can be frightening for families and require prompt medical intervention.

The original research paper highlights the diagnosis of a Japanese boy with FBPase deficiency, emphasizing the importance of genetic testing and careful management to improve outcomes. Understanding this condition and its genetic underpinnings is crucial for families and healthcare providers alike.

This condition, while rare (affecting 1-9 per 100,000 individuals), is triggered by factors such as fructose intake, fasting, and infections. Once diagnosed, the outlook for children with FBPase deficiency is generally excellent, provided that proper dietary measures and preventive strategies are consistently followed.

What is Fructose-1,6-Bisphosphatase (FBPase) Deficiency?

Surreal illustration of sugar molecules within a child's silhouette, symbolizing Fructose-1,6-bisphosphatase Deficiency.

FBPase deficiency is caused by mutations in the FBP1 gene, which provides the instructions for making the fructose-1,6-bisphosphatase enzyme. This enzyme plays a vital role in the liver and kidneys, where it helps regulate glucose production. When the enzyme is deficient, the body struggles to maintain stable blood sugar levels, especially during times of fasting or illness.

The original paper describes a specific case involving a young boy who experienced symptoms like drowsiness, a pale face, and rapid breathing. These symptoms prompted doctors to investigate further, eventually leading to a diagnosis of FBPase deficiency. The diagnostic process involved:

Blood Tests: Evaluating pH levels, bicarbonate, lactate, uric acid, glucose, ketone bodies, ammonia, and pyruvate.
Urine Tests: Analyzing for the presence of lactate and ketone bodies.
Imaging: CT scans to assess the liver for hepatomegaly and fatty changes.
Fructose Tolerance Test: Monitoring blood glucose, lactate, and uric acid levels after fructose intake.
Genetic Testing: Identifying mutations in the FBP1 gene.

In this particular case, genetic testing revealed that the boy had two novel mutations in the FBP1 gene, inherited from each parent. These mutations impaired the function of the FBPase enzyme, leading to the observed symptoms. Understanding the genetic basis of FBPase deficiency is essential for accurate diagnosis and family planning.

Looking Ahead: Management and Family Planning

Early diagnosis and management are crucial for individuals with FBPase deficiency. With appropriate dietary control, including limiting fructose and glycerol intake, and prompt treatment of hypoglycemic episodes, affected individuals can lead healthy lives. For families with a child diagnosed with FBPase deficiency, genetic counseling and carrier testing are recommended to assess the risk of recurrence in future pregnancies. This knowledge empowers parents to make informed decisions and prepare for the needs of their children.

About this Article -

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This article is based on research published under:

DOI-LINK: 10.1297/cpe.26.275, Alternate LINK

Title: A Japanese Boy With Fructose-1,6-Bisphosphatase Deficiency Who Had A Novel ≪I≫Fbp1≪/I≫ Mutation (P.Phe90Val)

Subject: Endocrinology

Journal: Clinical Pediatric Endocrinology

Publisher: Japanese Society for Pediatric Endocrinology

Authors: Keiko Nagahara, Daisuke Ariyasu, Junko Igaki, Yuki Hasegawa, Yukihiro Hasegawa

Published: 2017-01-01

Everything You Need To Know

What exactly is Fructose-1,6-Bisphosphatase (FBPase) Deficiency?

Fructose-1,6-bisphosphatase (FBPase) deficiency is a rare, inherited metabolic disorder where the body struggles to produce glucose from non-carbohydrate sources, a process known as gluconeogenesis. This happens because of mutations in the FBP1 gene, which provides instructions for making the fructose-1,6-bisphosphatase enzyme. When this enzyme is deficient, the body has trouble maintaining stable blood sugar levels, leading to potential health issues.

Why is it important to diagnose Fructose-1,6-Bisphosphatase (FBPase) Deficiency early?

Early diagnosis of Fructose-1,6-bisphosphatase (FBPase) deficiency is crucial because it allows for the implementation of appropriate dietary control, such as limiting fructose and glycerol intake. Prompt treatment of hypoglycemic episodes can prevent serious complications, and affected individuals can lead healthy lives. Genetic counseling and carrier testing are also recommended for family planning to assess the risk of recurrence in future pregnancies.

How is Fructose-1,6-Bisphosphatase (FBPase) Deficiency diagnosed?

Fructose-1,6-bisphosphatase (FBPase) deficiency is diagnosed through a combination of blood tests, urine tests, imaging (CT scans), a fructose tolerance test, and genetic testing. Blood tests evaluate pH levels, bicarbonate, lactate, uric acid, glucose, ketone bodies, ammonia, and pyruvate. Urine tests analyze for the presence of lactate and ketone bodies. CT scans assess the liver for hepatomegaly and fatty changes. The fructose tolerance test monitors blood glucose, lactate, and uric acid levels after fructose intake. Genetic testing identifies mutations in the FBP1 gene to confirm the diagnosis.

What are the common symptoms of Fructose-1,6-Bisphosphatase (FBPase) Deficiency that I should watch out for?

Symptoms of Fructose-1,6-bisphosphatase (FBPase) deficiency can include drowsiness, a pale face, and rapid breathing, especially during times of fasting or illness. These symptoms are often related to low blood sugar (hypoglycemia) accompanied by metabolic and lactic acidosis. The severity of symptoms can vary, but prompt medical intervention is important to prevent complications.

How is Fructose-1,6-Bisphosphatase (FBPase) Deficiency typically managed after diagnosis?

Management of Fructose-1,6-bisphosphatase (FBPase) deficiency involves dietary control, specifically limiting fructose and glycerol intake. It's also important to promptly treat any episodes of hypoglycemia to maintain stable blood sugar levels. Families with a child diagnosed with FBPase deficiency should consider genetic counseling and carrier testing to understand the risk of recurrence in future pregnancies. Adhering to these measures helps affected individuals lead healthier lives. Other aspects of management that were not mentioned may involve working with dieticians and constant communication with your doctor.