Prenatal Detection of PIK3CA-related Overgrowth Spectrum in Cultured Amniocytes Using Long-range PCR and Next-generation Sequencing.

Mutations in PIK3CA are associated with overgrowth spectrum disorders including excessive growth in some areas of the body and the central nervous system. Alterations in PIK3CA occur as somatic, postzygotic events and confer a mosaic genotype with variability in phenotypic expression being commonly observed. We describe the second reported prenatal diagnosis of a PIK3CA-related overgrowth spectrum disorder. The prenatal ultrasound features in this case enabled the presumptive, prospective diagnosis to be made which was then confirmed by genetic testing. Subsequent parental testing for mutations in PIK3CA demonstrated normal genotypes. Identification of this mutation prenatally enabled prospective information to be provided to the family and facilitated multidisciplinary perinatal management.