D-Bifunctional Protein Deficiency
D-BP deficiency is a disorder of peroxisomal fatty acid beta-oxidation affecting the HSD17B4 gene and follows an autosomal recessive mode of inheritance. Its prevalence is estimated at 1 in 100,000 individuals.
The pathology results in the accumulation in plasma of very long chain fatty acids (VLCFA), dihydroxy and trihydroxyesteric acid (DHCA and THCA) and pristanic and phytanic acid.
The clinical features are similar to those of Zellweger syndrome and include neonatal hypotonia, retinopathy, hearing loss, early-onset seizures, severe developmental delay, abnormal facial features and hepatomegaly or enlarged liver. Most patients die before the age of 2 years.
More recently, cases have been described of patients with later onset who may survive to adulthood. They usually present with gradual hearing loss, ataxia, peripheral neuropathy and other neurological disorders.
There is no specific treatment for this disease and available treatments focus on supporting patients to facilitate their nutrition and alleviate symptoms associated with the nervous system such as ataxia and seizures.