D-bifunctional protein deficiency associated with drug resistant infantile spasms

Peroxisomal disorders appear with a frequency of about 1:5000 in newborns. Peroxisomal D-bifunctional protein (D-BP), encoded by the HSD17B4 gene (gene ID: 3294; locus tag: HGNC:5213, chromosome 5q2; official symbol: HSD17B4; name: hydroxysteroid (17-β) dehydrogenase; gene type: protein coding) (OMIM *601860), comprises an 80 kDa multifunctional enzyme involved in peroxisomal β-oxidation of certain fatty acids and the synthesis of bile acids. Its deficiency causes a very severe, Zellweger-like clinical phenotype and most patients die within the first year of life. In this paper, we report a case of D-BP deficiency in a patient with two heterozygous trinucleotide deletions (233_235 del AAG and 824_826 del AGA) in the HSD17B4 gene. The patient suffered from a peculiar epileptic phenotype (i.e. a West syndrome with a “modified hypsarrhythmic pattern” – Hrachovy et al. Epilepsia 1984;25:317–25), clinically appearing as drug-resistant asymmetric spasms. Vigabatrin seemed the most effective among the antiepileptic drugs. The patient died at the age of 23 months owing to respiratory complications. To date, only a few patients with D-BP deficiency have been described in the literature. This case adds to our knowledge of the clinical presentation of bifunctional protein deficiency.