Eyes See what the Mind Knows: Clues to Pattern Recognition in Single Enzyme Deficiency-Related Peroxisomal Disorders

Peroxisomal disorders are a heterogeneous group of inborn errors of metabolism that result in impaired function of the peroxisome. Within this, single enzyme deficiencies are known to cause a constellation of symptoms not very different from the peroxisome biogenesis defects. Thus, there is a need to identify features that differentiate the two. We present 3 molecularly confirmed families: 1 with Acyl CoA oxidase deficiency and 2 with D-bifunctional protein deficiency. The clinical, biochemical, and radiological features of these patients have been discussed. We attempt to highlight the overlap in facial features as well as strikingly similar MRI findings of cerebellar atrophy and white matter hyperintensities. This unique clinical profile will not only help in reaching a quick diagnosis, but in this era of variants of uncertain significance, it will prove as supporting evidence. Finally, we expand the genotypic spectrum with a description of 3 homozygous novel mutations (HSD17B4: c.670C>T, c.1807T>C; ACOX1: 1.03-kb exonic deletion) and discuss the role of protein modeling its establishing pathogenicity.