D-Bifunctional Protein Deficiency

Gene : HSD17B4

What is D-Bifunctional Protein Deficiency?

D-Bifunctional Protein Deficiency is an inherited neurological disorder characterized by weak muscle tone and seizures in newborns. Most infants are unable to learn developmental skills such as how to crawl or walk, and those that do may eventually lose these skills. Other common features include vision and hearing loss, brain abnormalities and dysmorphic facial features. The majority of children with D-Bifunctional Protein Deficiency do not survive beyond two years, but cases older than 7.5 years have been reported. Those that do survive beyond the first year have severe intellectual disability. D-bifunctional protein deficiency is caused by pathogenic variants in the HSD17B4 gene.

How is D-Bifunctional Protein Deficiency inherited?

D-Bifunctional Protein Deficiency is inherited in an autosomal recessive manner. This type of inheritance requires the presence of two copies of a pathogenic variant in the gene for a person to have the genetic disease. Both parents must be carriers of a pathogenic variant in the gene in order to be at risk to have an affected child. The child must inherit a pathogenic variant from each carrier parent in order to be affected. There is a 1 in 4 chance that a baby will inherit two mutated copies of the gene and be affected when both parents are carriers.

What does it mean to be a carrier?

There are generally no signs or symptoms associated with being a carrier for D-Bifunctional Protein Deficiency. However, the risk to have a child affected with these disorders is increased. Testing of reproductive partners is recommended for carriers of D-Bifunctional Protein Deficiency.

How common is D-Bifunctional Protein Deficiency in general population?

D-Bifunctional Protein Deficiency occurs in 1 in 100,000 newborns.

Family References and Resources
Clinician References
What is Analyzed?
  • Full gene sequencing
Affected Systems






Carrier Rates
Detection Rate
Carrier Frequency
General population > 81% 1 in 158

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