In 2004, it was reported that a single-nucleotide polymorphism in the 3′-UTR of the claudin-5 locus (rs10314) was weakly associated with schizophrenia in a Han Chinese population.28 This weak nominal association was also observed in other studies.29,30,31 Following sequencing across the remaining claudin-5 allele from a cohort of 67 22q11DS patients, a weak nominal association (*P=0.0388, two-sided χ2-test) between the claudin-5 variant (rs10314) and those 22q11DS patients who went on to develop schizophrenia was observed (Figure 1c). Here, CLDN5 is linked to 22q11.2 deletion syndrome.