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Sialuria
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Condition

Sialuria

Sialuria is a rare metabolic disorder caused by the overproduction of sialic acid, leading to developmental delays and distinctive physical features.

Overview

Sialuria is a rare disorder that affects development. Infants with the condition are often born with neonatal jaundice, an enlarged liver and spleen (hepatosplenomegaly), and unusually small red blood cells (microcytic anemia). They may also exhibit a flat face and "coarse" facial features, along with temporarily delayed development and weak muscle tone (hypotonia).

Symptoms

The features of sialuria vary widely among affected individuals. Common clinical observations include:

  • Early childhood: Frequent upper respiratory infections and episodes of dehydration and stomach upset (gastroenteritis).
  • Older children: Potential for seizures and learning difficulties.
  • Variable outcomes: Some affected children may have nearly normal intellectual development. Many problems appear to improve with age, and some adults may have such mild symptoms that they never come to medical attention.

Causes

Variants in the GNE gene cause sialuria. This gene provides instructions for making an enzyme involved in the chemical pathway that produces sialic acid, a sugar that modifies molecules on the surface of cells to influence functions like cell migration, adhesion, signaling, and inflammation.

Normally, a feedback system shuts off the GNE enzyme when sufficient sialic acid is produced. In sialuria, gene variants disrupt this feedback mechanism, resulting in the overproduction of sialic acid. This excess sugar builds up within cells and is excreted in urine. Researchers are currently investigating how this accumulation interferes with normal development.

Inheritance

Sialuria is inherited in an autosomal dominant pattern, meaning one copy of the altered gene in each cell is sufficient to cause the disorder. Most reported cases have occurred in people with no known family history, likely representing new (de novo) variants that occurred during the formation of reproductive cells or early embryonic development.

Frequently Asked Questions

Many children experience a gradual reduction in infection frequency and stabilization of growth, though learning difficulties may persist. Regular monitoring by a pediatric neurologist, hematologist (for anemia), and developmental specialist is advised—typically every 6‑12 months—to adjust therapies and screen for emerging complications such as seizures.
Because upper‑respiratory infections and gastroenteritis are common, prompt treatment of fevers and maintaining adequate hydration are crucial. Parents should ensure timely vaccinations, avoid exposure to sick contacts when possible, and have an action plan for rapid rehydration (oral rehydration solutions or IV fluids if needed).
Sialuria follows an autosomal‑dominant inheritance pattern, so each pregnancy carries a 50 % risk of inheriting the mutant allele and developing the disorder, regardless of the child’s sex. Genetic counseling is recommended for family planning.
Diagnosis combines biochemical testing (elevated free sialic acid in urine measured by mass spectrometry) with molecular genetic testing of the GNE gene. A positive urine screen prompts sequencing of GNE to identify the pathogenic variant.
There is no disease‑specific cure, but supportive care can help. Physical and occupational therapy address hypotonia and motor delays; speech therapy assists with language development. Some clinicians trial oral sialic‑acid‑reducing agents or dietary modifications, but evidence is limited, so management is individualized.
Source: MedlinePlus, National Library of Medicine

MedlinePlus brings together authoritative health information from the National Library of Medicine (NLM), the National Institutes of Health (NIH), and other government agencies and health-related organizations.

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