Developmental delay: Gene testing

Abstract

Although the classic childhood phenotypes of many developmental disorders have been established for some time, only recently have the genetic etiologies of some of these disorders been identified. Understanding the genetic basis of these disorders allows for molecular confirmation of the clinical diagnosis in an individual which can then be utilized for risk counseling and prenatal testing. This chapter reviews the molecular basis, clinical utility, testing strategy, and interpretation of clinical molecular tests for single-gene causes of developmental delay, which include fragile X syndrome, Angelman syndrome, Rett syndrome, Noonan spectrum disorders, and X-linked intellectual disability.