PHOX2B polyalanine repeat mutation has a profound impact on the transcriptome of neuronal progenitor cells in Haddad syndrome

Mutation in paired-like homeobox 2B (PHOX2B) is used as the diagnostic marker of Haddad syndrome (HS). The mutant gene/protein afflict neural crest cells during embryonic development which leads to congenital central hypoventilation syndrome (CCHS) and Hirschsprung's disease (HSCR). Previous studies on HS and CCHS have mainly focused on the conformational dynamics of the mutant protein and have remained controversial. Here we performed RNA-sequencing on the patient derived neuroepithelial stem cells (NESCs), pertinent to the neurodevelopmental phenotype in HS, and found that the PHOX2B-PARM has a profound impact on the transcriptional profile of the cells. The single copy of PHOX2B-PARM in heterozygote cells were leading to >10 fold differentially expressed genes. In the patient cells there was a significant enrichment of genes related to neuronal development and synapse organization mainly driven by L1CAM interactions and synaptogenesis signaling pathway. Our result not only highlight the use of a suitable model of HS but also provide a clear path for future experimental validation and downstream targets with potential therapeutic values.