D-Bifunctional Protein Deficiency—Metabolic Disorders

Metabolism is the process your body uses to get or make energy from the food you eat. Food is made up of proteins, carbohydrates, and fats. Chemicals in your digestive system break the food parts down into sugars and acids, your body’s fuel. Your body can use this fuel right away, or it can store the energy in your body tissues, such as your liver, muscles, and body fat.

A metabolic disorder occurs when abnormal chemical reactions in your body disrupt this process. When this happens, you might have too much of some substances or too little of other ones that you need to stay healthy. There are different groups of disorders. Some affect the breakdown of amino acids, carbohydrates, or lipids. Another group, mitochondrial diseases, affects the parts of the cells that produce the energy.

You can develop a metabolic disorder when some organs, such as your liver or pancreas, become diseased or do not function normally. Diabetes is an example.

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• Metabolic acidosis (Medical Encyclopedia)
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D-bifunctional protein deficiency is a disorder that causes deterioration of nervous system functions (neurodegeneration) beginning in infancy. Newborns with D-bifunctional protein deficiency have weak muscle tone (hypotonia) and seizures. Most babies with this condition never acquire any developmental skills. Some may reach very early developmental milestones such as the ability to follow movement with their eyes or control their head movement, but they experience a gradual loss of these skills (developmental regression) within a few months. As the condition gets worse, affected children develop exaggerated reflexes (hyperreflexia), increased muscle tone (hypertonia), more severe and recurrent seizures (epilepsy), and loss of vision and hearing. Most children with D-bifunctional protein deficiency do not survive past the age of 2. A small number of individuals with this disorder are somewhat less severely affected. They may acquire additional basic skills, such as voluntary hand movements or unsupported sitting, before experiencing developmental regression, and they may survive longer into childhood than more severely affected individuals.Individuals with D-bifunctional protein deficiency may have unusual facial features, including a high forehead, widely spaced eyes (hypertelorism), a lengthened area between the nose and mouth (philtrum), and a high arch of the hard palate at the roof of the mouth. Affected infants may also have an unusually large space between the bones of the skull (fontanelle). An enlarged liver (hepatomegaly) occurs in about half of affected individuals. Because these features are similar to those of another disorder called Zellweger syndrome (part of a group of disorders called the Zellweger spectrum), D-bifunctional protein deficiency is sometimes called pseudo-Zellweger syndrome.