Nearly all WNK1 mutations that cause HSANIIA are located in HSN2, a nervous system-specific exon of the gene (Shekarabi et al., 2008).
In a functional analysis of WNK1 in the nervous system, Bercier et al., 2013 report that WNK1/HSN2 knockdown affects expression of the chloride transporter KCC2 in zebrafish embryos, sugesting a possible pathway for the mutants' neurodevelopmental effects.