D-Bifunctional Protein Deficiency

17 Beta-Hydroxysteroid Dehydrogenase IV Deficiency; DBP Deficiency; Peroxisomal Bifunctional Enzyme (PBFE) Deficiency


Autosomal recessive

Inheritance from both parents will result in the disease

Age range at onset:


Specialists you may see:


This condition, beginning in infancy, causes neurodegeneration, with most babies never acquiring developmental skills. Those who learn basic skills such as the ability to control head movement or follow movement with their eyes will see these skills deteriorate within a few month. Some who are less severely affected may be able to move their hands voluntarily or sit unsupported before experiencing developmental regression.

Hypotonia and seizures are common, and worsen over time. Hyperreflexia occurs in later stages, alongside increased muscle tone and a loss of vision and hearing. Most affected children do not survive past the age of two, some who are not so severely affected may live longer into childhood.

Around half of those affected will suffer from hepatomegaly. Some have macrocephaly, abnormally large fontanelles, as well as unusual facial features such as a high forehead, retrognathism, low set ears and widely spaced eyes.


Mutations in the HSD17B4 gene cause this condition, as this gene should produce D-Bifunctional Protein. D-Bifunctional protein is involved in the breakdown of fatty acids; without it, these accumulate. These fatty acids may cause abnormal brain development and the breakdown of myelin (white matter), causing the symptoms described.

These features are similar to Zellweger syndrome, the condition is sometimes referred to as Pseudo-Zellweger syndrome.