The major soluble NRXN3 isoform, encoded by the exon 22a-23a variant mRNA was also decreased by 63% and 71% in AD patients with CC and CC/TT genotypes when compared with those in control individuals with CC genotypes (Fig. 4d; P < 0.0001 by two-tailed Mann-Whitney test for both comparisons). Here, NRXN3 is linked to Alzheimer disease.