PEX6 Mutation in a Child with Infantile Refsum Disease-A Case Report and Literature Review

Abstract

The aim of this paper is to describe the temporal progression and clinical picture of a 2-year-old child with infantile Refsum disease, as well as the diagnostic procedures performed; this case presented multiple hematologic, metabolic, and developmental complications and progressive disabilities. Genetic testing revealed a mutation of the PEX6 (Peroxisomal Biogenesis Factor 6) gene, and the metabolic profile was consistent with the diagnosis. Particularly, the child also presented altered coagulation factors and developed a spontaneous brain hemorrhage. The clinical picture includes several neurological, ophthalmological, digestive, cutaneous, and endocrine disorders as a result of the very long chain fatty acid accumulation as well as secondary oxidative anomalies. The study of metabolic disorders occurring because of genetic mutations is a subject of core importance in the pathology of children today. The PEX mutations, difficult to identify antepartum, are linked to an array of cell anomalies with severe consequences on the patient's status, afflicting multiple organs and systems. This is the reason for which our case history may be relevant, including a vast number of symptoms, as well as modified biological parameters.

Keywords: PEX6 mutation; infantile Refsum disease; metabolic anomalies; peroxisome biogenesis disorder.

Figure 1

Phytanic acid enzymatic steps of alpha-oxidation [12,13,14]. 1. On the cytosolic side of the peroxisomes, phytanic acid is activated by an acyl-CoA synthetase, resulting in phytanoyl-CoA, which is transported into the peroxisome by a specific transporter protein. 2. Phytanoyl-CoA is oxidized by phytanoyl-CoA hydroxylase, producing 2-hydroxyphytanoyl-CoA. 3. 2-hydroxyphytanoyl-CoA is then dehydrogenated by the enzyme 2-hydroxyphytanoyl-CoA lyase, resulting in pristanaldehide. 4. Pristanaldehide is oxidized by pristanal dehydrogenase, which converts it to pristanic acid.