Integration of microarray technology into prenatal diagnosis: counselling issues generated during the NICHD clinical trial.

Cytogenetic microarray analysis (CMA) in prenatal testing detects chromosome abnormalities and new genetic syndromes that would be missed by conventional cytogenetics and has the potential to significantly enhance prenatal genetic evaluation. A large Eunice Kennedy Shriver National Institute Of Child Health and Human Development (NICHD)-sponsored multicentered trial to assess the role of CMA as a primary prenatal diagnostic tool has been completed, and results will soon be available. Integration of this technology into clinical care will require thoughtful changes in patient counseling. Here, we examine four cases, all ascertained in the NICHD prenatal microarray study, to illustrate the challenges and subtleties of genetic counseling required with prenatal CMA testing. Although the specifics of each case are distinct, the underlying genetic principles of uncertainty, variable expressivity, and lack of precise genotype-phenotype correlation are well known and already part of prenatal counseling. Counselor and practitioner education will need to include both the science of interpreting array findings as well as development of improved approaches to uncertainty. A team approach to interpretation will need to be developed, as will standardized guidelines by professional organizations and laboratories. Of equal import is additional research into patient attitudes and desires, and a better understanding of the full phenotypic spectrum of copy number variants discovered in utero.