A missense mutation Leu309Met in the WKL1 (MLC1, KIAA0027) gene, mapped to 22q13.3, was reported to co-segregate with periodic catatonic schizophrenia (SCZ) in a single large German pedigree with seven affected individuals (Meyer et al. [2001 Mol Psychiatry 6302-306]). This report raised the following questions that were dealt with in the present study does the Leu309Met mutation have a role in SCZ, or only in catatonic SCZ? Does the mutation Leu309Met in the WKL1 gene, encoding a putative membrane protein, non-selective cation channel, have any effect on the channel activity? Is the WKL1 gene, which is expressed exclusively in brain, expressed differently in SCZ brains compared to controls? These questions were answered by screening the Leu309Met mutation in 117 Israeli Jewish patients with SCZ (55 Ashkenazi and 62 non-Ashkenazi Jews) and 176 matched controls. In search of differences in the level of WKL1 gene expression, postmortem dorsalateral prefrontal cortex of 16 schizophrenic patients and 15 controls was checked. We also measured the putative channel activity of normal WKL1 subcloned in pcDNA3 to determine the effect of the reported Leu309Met mutation. Our results argue against the involvement of WKL1 in SCZ susceptibility.