Single-nucleotide polymorphisms (SNPs) and differential expression patterns of NTNG1 and NTNG2 have been associated with schizophrenia and bipolar disorder in humans.18, 19, 20 A de novo genomic rearrangement involving NTNG1 was proposed to potentially cause features of Rett syndrome in an isolated individual.21 This evidence concerns the gene NTNG1 and Rett syndrome.