Use of chromosomal microarray in obstetrics gas station car wash

Prenatal diagnosis and postnatal evaluation of pregnancy loss often involves cytogenetic analysis of amniocytes, chorionic villi, or fetal cells. Although conventional Giemsa(G)-banding of metaphase chromosomes detects aneuploidies and large structural changes (eg, balanced or unbalanced translocations, inversions), this approach also has limitations: it does not consistently identify submicroscopic (ie, smaller than what is visible under a light microscope) genomic defects (<3 to 10 million base pairs [Mb]) and requires cell culture, which takes a minimum of seven days to obtain an adequate number of dividing cells. The use of fluorescence in situ hybridization (FISH) reduces the time to obtain a result and is less labor intensive, but can only detect a limited number of pre-specified targets.

Chromosomal microarray (CMA) is an array-based molecular cytogenic technique that can overcome some limitations of a karyotype, and is particularly useful for its ability to detect submicroscopic gains and losses on every chromosome ( figure 1) and to provide results from products of conception when cells do not grow in culture. This technique compares the genomic content (DNA) of a patient (target) with that of a normal control individual (or individuals) and detects gains and losses (duplications and deletions) ranging in size from very large, including aneuploidy of entire chromosomes, to very small (typically as small as about 200,000 base pairs or 0.2 Mb). Gains and losses may correspond to structural changes such as unbalanced translocations), but CMA cannot detect the physical location of the extra material (as in a translocation) nor can it detect structural chromosome changes that do not result in deletions or duplications (eg, balanced translocations or balanced inversions). Different laboratories perform CMA using different technology platforms and with different array design and content [ 1-7].

• Kalia SS, Adelman K, Bale SJ, et al. Recommendations for reporting of secondary findings in clinical exome and genome sequencing, 2016 update (ACMG SF v2.0): a policy statement of the American College of Medical Genetics and Genomics. Genet Med 2017; 19:249.

• Committee on Genetics and the Society for Maternal-Fetal Medicine. Committee Opinion No.682: Microarrays and Next-Generation Sequencing Technology: The Use of Advanced Genetic Diagnostic Tools in Obstetrics and Gynecology. Obstet Gynecol 2016; 128:e262.

• Scott F, Murphy K, Carey L, et al. Prenatal diagnosis using combined quantitative fluorescent polymerase chain reaction and array comparative genomic hybridization analysis as a first-line test: results from over 1000 consecutive cases. Ultrasound Obstet Gynecol 2013; 41:500.

• de Wit MC, Srebniak MI, Govaerts LC, et al. Additional value of prenatal genomic array testing in fetuses with isolated structural ultrasound abnormalities and a normal karyotype: a systematic review of the literature. Ultrasound Obstet Gynecol 2014; 43:139.

• Srebniak MI, Joosten M, Knapen MFCM, et al. Frequency of submicroscopic chromosomal aberrations in pregnancies without increased risk for structural chromosomal aberrations: systematic review and meta-analysis. Ultrasound Obstet Gynecol 2018; 51:445.

• Hillman SC, Pretlove S, Coomarasamy A, et al. Additional information from array comparative genomic hybridization technology over conventional karyotyping in prenatal diagnosis: a systematic review and meta-analysis. Ultrasound Obstet Gynecol 2011; 37:6.

• Novelli A, Grati FR, Ballarati L, et al. Microarray application in prenatal diagnosis: a position statement from the cytogenetics working group of the Italian Society of Human Genetics (SIGU), November 2011. Ultrasound Obstet Gynecol 2012; 39:384.