a modestly-sized sample (40 MZ pairs and 30 DZ pairs), therefore these point estimates should be interpreted with some caution. Importantly, a recent case-control study confirmed high test-retest reliability of MMN and has assigned this measure one of the highest ranks among other potential endophenotypes for schizophrenia, based on three criteria including state independence, long-term stability, and magnitude of deficits is patients relative to controls (Light et al., 2012). Unfortunately, heritability, a crucial criterion for endophenotype, was not included in this study's rating system. Evidence for heritability of MMN remains scarce, and replication on larger samples by independent laboratories is needed before a definitive conclusion about endophenotype value of this measure can be made.
