The unfortunate deaths of a number of children who were medicated with codeine is increasing interest in gene duplications. As reported in Pediatrics, These children died after receiving what would have been considered safe doses of codeine after minor surgery. Codeine is metabolized into morphine in the human body, and tests showed high blood levels of morphine that would normally indicate that these children had received much higher doses. Investigation revealed that some of these children had gene duplications that included CYP2D6, a gene that produces an enzyme that converts codeine to morphine. As a result these children were ultrametabolizers, converting codeine to morphine much more quickly than expected. Other studies have suggested that this gene duplication is fairly common.
The significance of this for MECP2 Duplication Syndrome is indirect. This discovery provides another example of how gene duplications can be clinically significant, and provides further rationale for widespread testing, and perhaps in the long-term moves the agenda forward toward full genome testing of more individuals in the future.