Is it possible in a nasopharyngeal specimen genes of neural system to be expressed? For example, genes about neural differentiation?
This paper mentions using a cytology brush (not the usual NP swab) to obtain cells from the olfactory epithelium. They obtained and cultured neural precursor cells. Have a look.
Trends in molecular medicine.
"The Olfactory Neural Epithelium as a Tool in Neuroscience"
Joëlle Lavoie, Patricia Gassó Astorga, [...], and Koko Ishizuka