The NF2 gene is mutated or homozygously deleted in 40–50% of MM,16, 32, 45 although established primary and commercial cell lines show more frequent rates of mutation or undetectable protein.46 Comparison of NF2 gene copy number and its product Merlin, highlighted the importance of transcriptional silencing and posttranslational modification in MM,46; in seven out of eight primary cell lines it was observed that, despite at least one allele being retained, Merlin was undetectable. The gene discussed is NF2; the disease is Miyoshi myopathy.