Overgrowth syndrome

This chapter describes overgrowth syndromes. It begins by introducing the three different types of phenotypes for this group of diseases: prenatal overgrowth, postnatal overgrowth, and segmental overgrowth. Overgrowth syndromes can be associated with various causes such as hormone imbalance, life-threatening hypoglycemia (e.g., Beckwith-Wiedemann Syndrome, BWS), seizures (Sotos syndrome), developmental delay (Sotos syndrome, Weaver syndrome), and increased susceptibility to malignancy (Wilms’ tumor, hepatoblastoma, etc.). Next, it discusses challenges to the diagnosis of somatic overgrowth syndrome as part of segmental overgrowth syndrome due to genetic and phenotypic heterogeneity, low-level mosaicism, and/or tissue-specific manifestation. Finally, the chapter shows how to identify the gene mutations associated with overgrowth syndrome by using advanced molecular technology including karyotyping, FISH, and next-generation sequencing, which are illustrated in two clinical cases.