Screening for genetic disorders.

INTRODUCTION: Cerebral malformations can be genetically determined and/or part of complex syndromes. When the defect is detected during pregnancy, it important to rule out an associated genetic condition. Family history and detailed examination of fetal anatomy are needed. DISCUSSION: Intrauterine growth retardation, as well as limb abnormalities (especially polydactyly) are strong indicators of a genetic condition in the context of a fetal cerebral malformation. A standard chromosomal analysis is needed in all cases. Fluorescent in situ hybridization (FISH) techniques using locus-specific probes that permit the detection of subtle chromosomal rearrangements and metabolic analyses may be indicated when a specific condition is suspected. As for molecular analyses, they have so far been mainly applicable to pregnancies at risk of a known disorder because of family history. The diagnosis consists of determining whether the fetus has inherited the causative mutation identified in the index case. When termination of pregnancy is elicited, a careful prenatal and postnatal examination is needed in order to give accurate genetic counseling for further pregnancies. Storage of fetal material allowing further molecular analyses is strongly recommended.