Genetic Testing in Mosaicism

Mosaicism due to postzygotic mutations is more common than considered before the era of massive parallel sequencing. In the clinical dermatologic practice, it is important to recognize skin lesions and syndromes caused by genetic mosaicism, to initiate genetic testing and counsel the patient and families regarding prognosis and risk of transmission to the offspring. Precise diagnosis and identification of the dysregulated pathway are also the basis for therapeutic interventions. Here we address the questions why, when, and how to perform genetic testing for mosaic skin conditions.