MAOA and neuroblastoma: This problem is made more difficult as the MAOA locus has been proposed as one of the loci that can escape X inactivation.12, 13, 14 To address the mechanisms which might underpin allele expression in the female we took advantage of the human neuroblastoma‐derived SH‐SY5Y cell line which has a female karyotype and is heterozygous for the uVNTR.