Bifunctional enzyme deficiency

What it is

A rare peroxisomal beta-oxidation disorder characterized by deficiency of peroxisomal D-bifunctional protein, type 1 being caused by deficiency of both dehydrogenase and hydratase activities of the enzyme, and types 2 and 3 by hydratase or dehydrogenase deficiency alone, while type 4 is due to compound heterozygous mutations affecting both units and represents a clinically milder phenotype. Types 1-3 are typically fatal in infancy. Patients present with early onset of generalized hypotonia, seizures, severe global developmental delay, craniofacial dysmorphism (large fontanel, high forehead, hypertelorism, epicanthal folds) and elevated plasma very long chain fatty acids. Variable features include hepatomegaly, polymicrogyria, and cerebral white matter abnormalities, among others.

Key facts

Prevalence

<1 / 1 000 000

Age of onset

Infancy

Inheritance

Autosomal recessive

Classified as

Disease

Prevalence figures describe populations, not individuals, and are often estimates from a single study. Where the figure is an incidence or a birth prevalence, it says so.

Genes

ICD-10 codes

ICD-10 has no distinct code for most rare diseases, so many are filed under the nearest available one. A shared code identifies the group, not this disease — the ORPHAcode above is what identifies it.

Related health topics

Reached through the ICD-10 categories this disease is filed under, so these describe the broader group rather than this disease specifically.

Cross-references