Causes of Congenital Malformations

Abstract

Congenital malformations are structural abnormalities due to faulty development, present at birth, and amongst the major causes of prenatal, perinatal and infant mortality and morbidity. They include gross and microscopic malformations, inborn errors of metabolism, intellectual disability and cellular and molecular abnormalities. About 3% of newborns have a single major malformation, and 0.7% have multiple major defects. The frequency is much higher prenatally, the majority aborting spontaneously. More than 80% of malformed conceptuses are lost during the embryonic period, and more than 90% before birth. The importance of congenital malformations as a cause of perinatal mortality has increased as deaths from intrapartum problems and infectious diseases have declined, and better neonatal care has improved the survival of normally developed low-birthweight babies. During the last decades, there has been a rapid expansion of methods for detecting many different types of disorders prenatally. In this introductory chapter, the known causes of congenital malformations (• Sect. 3.2), and possibilities to detect them prenatally (• Sect. 3.3), will be outlined. Some emphasis is given to the increasing group of inborn errors of metabolism affecting the central nervous system (CNS; • Sect. 3.4), disorders of white matter (• Sect. 3.5), vascular disorders (• Sect. 3.6) and congenital tumours (• Sect. 3.7). Several Clinical cases illustrate these disorders. In • Sect. 3.8, classifications of CNS malformations are discussed.