Simpson-Golabi-Behmel Syndrome

Simpson-Golabi-Behmel syndrome was described independently by three groups of authors and eventually received its current designation by the author of this chapter. Among all the conditions described in this book, it is the only one to have X-linked inheritance, with possible expression in some carrier females. Therefore, the description of the clinical phenotype is subdivided into two parts, one pertaining to males, the other to females. Typically present in both affected males and females is a “coarseness” of the facial traits, in addition to a number of congenital malformations that can affect the heart, the diaphragm, and the skeleton. Differential diagnosis and recurrence risks are clearly delineated. The genetic cause is described in detail and the pathogenic mechanism is illustrated by an explanatory cartoon.