Mosaic GNAQ and GNA11 mutations may cause phacomatosis melanorosea and phacomatosis melanocesioflammea

To the editor: In a recent article published in Pediatric Investigation, Zhang et al. reported a case series of phacomatosis pigmentovascularis (PPV).1 Among such cases, one was described as featuring an extensive lateralized telangiectatic nevus, a large hypermelanotic patch and a Klippel-Trenaunay phenotype; and another an extensive lateralised telangiectatic nevus, a nevus anemicus, an extensive nevus cesius, a large hypermelanotic patch and a Sturge-Weber-Klippel-Trenaunay phenotype.1 These cases were diagnosed as unclassifiable PPV and phacomatosis cesioflammea; instead, their clinical features are compatible with phacomatosis melanorosea (PMR) and phacomatosis melanocesioflammea (PMCF), respectively.2 The mosaic genetic defect causing these two exceedingly rare PPV variants is unknown so far. Quite remarkably, Zhang et al. reported that the patient with possible PMR was affected by a GNAQ c.548G>A (p.R183Q) mutation, while the patient with possible PMCF had a mosaic GNA11 c.547C>T (p.R183C) mutation.1 It is worth mentioning that these mutations are identical to those identified for another two PPV types, i.e. phacomatosis cesioflammea (GNAQ) and phacomatosis cesiomarmorata (GNA11).3 Notwithstanding a less-than-exhaustive clinical and molecular characterization of their cases, Zhang et al. might have indeed uncovered the gene alteration underlying PMR and PMCF. The blossoming of studies on clinical-genetic correlations of mosaic disorders in recent years leaves one hopeful that further confirmation will follow. The author declares no conflict of interest.