Neonatal Onset Seizures and Hypotonia Due to D-Bifunctional Protein Deficiency.

Peroxisomal disorders (PDs) are a diverse group of inherited conditions arising from impaired function of a specific peroxisomal enzyme, metabolite transporter, or defect in the peroxisome biogenesis system. Peroxisomal D-bifunctional protein (DBP) deficiency is generally classified as a Zellweger-like syndrome. This disorder is caused by mutations in the HSD17B4 gene, and only a limited number of confirmed cases have been reported to date.The authors report case of a 6-mo-old female infant presenting with neonatal-onset intractable seizures, characteristic facial features, hypotonia, and progressive hepatomegaly. An acylcarnitine profile revealed elevated very long-chain fatty acids, prompting the initiation of a medium-chain triglyceride (MCT) formula. Remarkably, this treatment led to seizure control, improved muscle tone, and a reduction in liver size. Whole exome sequencing identified a homozygous missense mutation in the HSD17B4 gene (c.1444A>T).This case suggests that MCT-containing formulas may offer therapeutic potential in the treatment of D-bifunctional protein deficiency.