More symptom information
Learn more about specific symptoms of this leukodystrophy in these pages.
17 Beta-Hydroxysteroid Dehydrogenase IV Deficiency; DBP Deficiency; Peroxisomal Bifunctional Enzyme (PBFE) Deficiency
D-Bifunctional Protein Deficiency is a rare genetic disorder characterised by the accumulation of fatty acids leading to neurodegeneration. It presents in infancy and is caused by mutations in the HSD17B4 gene. Symptoms include weak muscle tone, seizures, developmental regression, loss of vision and hearing, and may have unusual facial features. It is sometimes called pseudo-Zellweger syndrome as it presents similarly to Zellweger syndrome. Treatment mainly focuses on managing symptoms and providing supportive care to improve the individual’s quality of life.
A new diagnosis can be overwhelming as it brings unique challenges and adjustments, but it is important to remember that you are not alone.
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 and fatty acid derivatives in the peroxisome; without it, these accumulate. These fatty acids may cause abnormal brain development and the breakdown of myelin (white matter), causing the symptoms described.
This is a type of peroxisomal disorder as is Zellweger syndrome which has similar features.
Autosomal recessive: In autosomal recessive conditions, two copies of the genetic mutation are needed to cause the condition. We all have two copies of every gene, one from our mother and one from our father. The parents of someone with an autosomal recessive condition both carry one copy of the gene with a genetic mutation. Therefore, someone with an autosomal recessive condition has two copies of the genetic mutation, one copy from each parent. Each child of parents that both carry the genetic mutation will have a 25% chance of having the condition, a 50% chance of carrying the genetic mutation (like the parent), and a 25% chance of not having the condition.
Genetic counselling is essential for affected families due to the inheritance pattern of the condition. This is available at hospitals and Regional Genetic Centres. Please contact your doctor if you have any questions.
Learn more about genetic testing and counselling here.
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. Spasticity may develop over time in some patients but others could develop a neuropathy with diminished reflexes. Some may also experience 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.
Learn more about specific symptoms of this leukodystrophy in these pages.
Although there is currently no specific treatment for this leukodystrophy, there is condition management information that may be useful for you in managing your or your loved ones leukodystrophy.
There may be a current clinical trial, natural history study or patient registry for your condition. Check our current research page and ask your specialist doctor for more information.
We understand that research is a significant priority and source of hope for the leukodystrophy community. There is more research in leukodystrophy now than ever before. Alex TLC actively promotes and supports research in a number of ways.
Every month we update our database of research summaries with the most recent research. This includes summaries of leukodystrophy articles, clinical trials and pharmaceutical press releases. Our summaries allow our community to read about relevant recent research developments in a format that is easily understood.
Learn about the ways in which we can help in the how we support you section. When you or a family member been diagnosed with a leukodystrophy it may be difficult to know where to go for more advice – this information could help.
Our services and equipment section is here to help leukodystrophy patients and their families manage their condition. All information is based on our knowledge of UK services, however, our team are happy to receive support requests from other countries – email us.
You may be introduced to many different medical professionals which you may find confusing. View our guide to the health and care professionals you may encounter, with short descriptions about what they do.
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