Editor—Standard genetic tests usually involve obtaining a blood sample for DNA extraction. Other commonly used sources of DNA are buccal cells1 (from a cheek scraping) and hair roots,2 which are viable alternatives to a blood sample and less invasive to obtain, particularly useful in children. Some genetic tests require full mutation screening (at least of the affected subject in a family) and this can be greatly simplified, particularly for large, multiexon genes, by screening the mRNA as opposed to the DNA.3 The reason for this is simple; the mRNA contains all the relevant sequence in a compact “ready to screen” package rather than the many discrete packages (exons) found in DNA. In addition, mRNA is one step further down the gene-protein pathway and can yield more relevant information on the effect of a mutation (at least with regard to splicing). The problem with using RNA …