Pre- and postnatal genetic testing by array-comparative genomic hybridization: genetic counseling perspectives

Recently, a new genetic test has been developed that allows a more detailed examination of the genome when compared with a standard chromosome analysis. Array comparative genomic hybridization (CGH microarray; also known as chromosome microarray analysis) in effect, combines chromosome and fluorescence in situ hybridization analyses allowing detection not only of aneuploidies, but also of all known microdeletion and microduplication disorders, including telomere rearrangements. Since 2004, this testing has been available in the Medical Genetics Laboratory at Baylor College of Medicine for postnatal evaluation and diagnosis of individuals with suspected genomic disorders. Subsequently, to assess the feasibility of offering CGH microarray for prenatal diagnosis, a prospective study was conducted on 98 pregnancies in a clinical setting comparing the results obtained from array CGH with those obtained from a standard karyotype. This was followed by the availability of prenatal testing on a clinical basis in 2005. To date, we have analyzed over 8000 cases referred to our clinical laboratory, including approximately 300 prenatal cases. With the clinical introduction of any new testing strategy, and particularly one focused on genetic disorders, issues of patient education, result interpretation, and genetic counseling must be anticipated and strategies adopted to allow the implementation of the testing with maximum benefit and minimum risk. In this article, we describe our experience with over 8000 clinical prenatal and postnatal cases of CGH microarray ordered by our clinical service or referred to the Baylor Medical Genetics Laboratory and describe the strategies used to optimize patient and provider education, facilitate clinical interpretation of results, and provide counseling for unique clinical circumstances.