SMFM Consult Series I #41The use of chromosomal microarray for prenatal diagnosis

Chromosomal microarray analysis is a high-resolution, whole-genome technique used to identifychromosomal abnormalities, including those detected by conventional cytogenetic techniques, aswell as small submicroscopic deletions and duplications referred to as copy number variants. Becausechromosomal microarray analysis has a greater resolution than conventional karyotyping, it candetect deletions and duplications down to a 50- to 100-kb level. The purpose of this document is todiscuss the technique, advantages, and disadvantages of chromosomal microarray analysis and itsindications and limitations. We recommend the following: (1) that chromosomal microarray analysis beoffered when genetic analysis is performed in cases with fetal structural anomalies and/or stillbirth andreplaces the need for fetal karyotype in these cases (GRADE 1A); (2) that providers discuss the benefitsand limitations of chromosomal microarray analysis and conventional karyotype with patients who areconsidering amniocentesis and chorionic villus sampling (CVS), and that both options should beavailable to women who choose to undergo diagnostic testing (GRADE 1B); (3) that pre- and posttestcounseling should be performed by trained genetic counselors, geneticists, or other providers withexpertise in the complexities of interpreting chromosomal microarray analysis results (Best Practice);(4) that patients be informed that chromosomal microarray analysis does not detect every geneticdisease or syndrome and specifically does not detect autosomal-recessive disorders associated withsingle gene point mutations, as well as that chromosomal microarray analysis can detect consanguinityand nonpaternity in some cases (Best Practice); (5) that patients in whom a fetal variant ofuncertain significance is detected by prenatal diagnosis receive counseling from experts who haveaccess to databases that provide updated information concerning genotype-phenotype correlations(Best Practice).

Last Reaffirmed: Aug 1, 2022