Plasma oxysterols: biomarkers for diagnosis and treatment in spastic paraplegia type 5

The phenotype of adult versus pediatric patients with inborn errors of metabolism

Until recently, inborn errors of metabolism (IEM) were considered a pediatric specialty, as emphasized by the term "inborn," and the concept of adult onset IEM has only very recently reached the adult medical community. Still, an increasing number of adult onset IEM have now been recognized, as new metabolomics and molecular diagnostic techniques have become available. Here, we discuss possible mechanisms underlying phenotypic variability in adult versus children with IEM. Specifically, phenotypic severity and age of onset are expected to be modulated by differences in residual protein activity possibly driven by various genetic factors. Phenotypic variability may also occur in the context of similar protein expression, which suggests the intervention of environmental, ontogenic, and aging factors.

Serum neurofilament light chain is increased in hereditary spastic paraplegias

Blood biomarkers are still largely missing in hereditary spastic paraplegias (HSPs). We here explored Neurofilament light chain (NfL) as a biomarker in HSP. Serum NfL was assessed in 96 HSP (63 genetically confirmed), 96 healthy control, and 33 ALS subjects by single molecule array (Simoa). Compared to controls, NfL was increased in HSP (P < 0.001), correlating with cross‐sectional disease progression (ρ = 0.28). Levels were lower than in ALS (P < 0.001), allowing to differentiate HSP from ALS (AUC = 0.91). Serum NfL might serve as a biomarker in HSP indicating neuronal damage and, if confirmed longitudinally, disease progression. It might also support differentiating HSP from ALS.

Converging cellular themes for the hereditary spastic paraplegias

Hereditary spastic paraplegias (HSPs) are neurologic disorders characterized by prominent lower-extremity spasticity, resulting from a length-dependent axonopathy of corticospinal upper motor neurons. They are among the most genetically-diverse neurologic disorders, with >80 distinct genetic loci and over 60 identified genes. Studies investigating the molecular pathogenesis underlying HSPs have emphasized the importance of converging cellular pathogenic themes in the most common forms of HSP, providing compelling targets for therapy. Most notably, these include organelle shaping and biogenesis as well as membrane and cargo trafficking.