ELP1 splicing correction reverses proprioceptive sensory loss in familial dysautonomia

Familial dysautonomia (FD) is a recessive neurodegenerative disease caused by a splice mutation in Elongator complex protein 1 (ELP1, also known as IKBKAP) which leads to variable skipping of exon 20 and to a drastic reduction of ELP1 levels in the nervous system. Clinically, many of the debilitating aspects of the disease are related to a progressive loss of proprioception, which leads to severe gait ataxia, spinal deformities and respiratory insufficiency due to neuromuscular incoordination. There is currently no effective treatment for FD and the disease is ultimately fatal. Development of a drug that targets the underlying molecular defect provides hope that the drastic peripheral neurodegeneration characteristic of FD can be halted. We demonstrate herein that the FD mouse, TgFD9; IkbkapΔ20/flox, recapitulates the proprioceptive impairment observed in individuals with FD, and we provide the in vivo evidence that postnatal correction of mutant ELP1 splicing promoted by the small molecule kinetin can rescue neurological phenotypes in FD. Daily administration of kinetin starting at birth improves sensory-motor coordination and prevents the onset of spinal abnormalities by stopping the loss of proprioceptive neurons. These phenotypic improvements correlate with increased levels of full length ELP1 mRNA and protein in multiple tissues including the peripheral nervous system (PNS). Our results show that postnatal correction of the underlying ELP1 splicing defect can rescue devastating disease phenotypes and is therefore a viable therapeutic approach for persons with FD. Both placebo and kinetin treatments were applied on six human FD fibroblast lines. Paired-end RNASeq was performed on these twelve fibroblast lines.