D-Bifunctional Protein Deficiency

Severe disorder of beta-oxidation of fatty acids in cellular peroxisomes causing neurodegeneration in infancy. It produces symptomatology similar to Zellweger syndrome such as seizures and liver dysfunction.

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.

Symptoms

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.

Disease management

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.

Genes analyzed

HSD17B4

Bibliography

Ferdinandusse S, Ylianttila MS, Gloerich J, et al . Mutational spectrum of D-bifunctional protein deficiency and structure-based genotype-phenotype analysis. Am J Hum Genet. 2006 Jan;78(1):112-24.

Mehtälä ML, Lensink MF, Pietikäinen LP, et al . On the molecular basis of D-bifunctional protein deficiency type III. PLoS One. 2013;8(1):e53688.

Yamamoto A, Fukumura S, Habata Y, et al . Novel HSD17B4 Variants Cause Progressive Leukodystrophy in Childhood: Case Report and Literature Review. Child Neurol Open. 2021 Oct 11;8:2329048X211048613.