Distinguishing gene variant severity for mild, severe, and atypical peroxisome biogenesis disorders in .

Peroxisomal biogenesis disorders (PBD) are autosomal recessive disorders caused by loss-of-function mutations of one of the genes responsible for peroxisomal formation. Impaired peroxisome assembly causes severe multisystemic failure with patient phenotypes ranging from epilepsy, liver disease, feeding issues, biochemical abnormalities, and neurodegeneration. Variants in the same gene can produce wide differences in severity, ranging from individuals with death in the first year of life to adults with milder complications.