Acral
burning pain triggered by
fever, thermal hyposensitivity and skin
denervation are hallmarks of
small fibre neuropathy in
Fabry disease, a life-threatening X-linked lysosomal storage disorder. Variants in the gene encoding
alpha-galactosidase A may lead to impaired
enzyme activity with cellular accumulation of
globotriaosylceramide. To study the underlying pathomechanism of Fabry-associated
small fibre neuropathy, we generated a neuronal in vitro disease model using patient-derived induced pluripotent stem cells from three Fabry patients and one healthy control. We further generated an isogenic control line via gene editing. We subjected induced pluripotent stem cells to targeted peripheral neuronal differentiation and observed intra-lysosomal
globotriaosylceramide accumulations in somas and neurites of Fabry sensory neurons using super-resolution microscopy. At functional level, patch-clamp analysis revealed a hyperpolarizing shift of
voltage-gated sodium channel steady-state inactivation kinetics in isogenic control neurons compared with healthy control neurons (P < 0.001). Moreover, we demonstrate a drastic increase in Fabry sensory neuron
calcium levels at 39°C mimicking clinical
fever (P < 0.001). This pathophysiological phenotype was accompanied by thinning of neurite calibres in sensory neurons differentiated from induced pluripotent stem cells derived from Fabry patients compared with healthy control cells (P < 0.001). Linear-nonlinear cascade models fit to spiking responses revealed that Fabry cell lines exhibit altered single neuron encoding properties relative to control. We further observed mitochondrial aggregation at
sphingolipid accumulations within Fabry sensory neurites utilizing a click chemistry approach together with mitochondrial dysmorphism compared with healthy control cells. We pioneer pilot insights into the cellular mechanisms contributing to
pain, thermal hyposensitivity and
denervation in Fabry
small fibre neuropathy and pave the way for further mechanistic in vitro studies in
Fabry disease and the development of novel treatment approaches.