MeCP2 R106W is a frequent Rett syndrome mutation causing severe phenotypes (Cuddapah et al., 2014) and the less common R106Q mutation was described to cause “classic” Rett syndrome (Bienvenu et al., 2000; Fukuda et al., 2005; Zahorakova et al., 2016), but there is insufficient clinical information reported for individuals with R106Q, R106G and R106L for a comparison of phenotypes (see RettBASE, (Krishnaraj et al., 2017)). The gene discussed is MECP2; the disease is Rett syndrome.