Chromosomal microarray

Chromosomal microarray is a genome-wide test that compares labeled DNA samples with probes across the genome to detect DNA gains and losses. It can identify copy-number changes too small to see under a microscope.

Array comparative genomic hybridization: A microarray method that compares patient and reference DNA to detect relative copy-number gains and losses. This is one of the two main probe-based strategies used in chromosomal microarray testing.
Prenatal genetic testing: Testing during pregnancy to assess fetal genetic or chromosomal conditions. Microarray can investigate fetal chromosome imbalances when prenatal testing is indicated.
Karyotype: A laboratory image and analysis of an individual’s chromosomes, typically arranged by size and shape. Karyotyping sees large chromosome changes but usually lacks microarray’s resolution for small copy-number changes.
Diagnostic yield: The proportion of tested cases in which a test provides a clinically useful diagnosis. Microarray increased diagnostic findings in groups with unexplained developmental conditions compared with conventional chromosome analysis.
Single-nucleotide polymorphism array: A DNA microarray that measures common single-base variants and can reveal copy-number changes and regions of homozygosity. This array strategy can detect copy-number changes and also expose patterns such as uniparental disomy.
Developmental delay: A significant lag in a child’s acquisition of age-expected developmental skills. Microarray is commonly used to investigate unexplained developmental delay for genomic gains and losses.
Chromosome microarray versus exome sequencing: A comparison of genome-wide copy-number testing with sequencing focused on protein-coding regions. Exome sequencing can find many small sequence variants that chromosomal microarray does not detect.
Incidental finding: A medically relevant result discovered unintentionally while testing for another purpose. Genome-wide analysis can reveal findings unrelated to the original clinical question.
Fluorescence in situ hybridization: A targeted method that uses fluorescent DNA probes to detect specific sequences in chromosomes or cells. Unlike genome-wide microarray testing, it generally answers a focused question about selected chromosome regions.
Congenital anomaly: A structural or functional condition present at birth that arises during prenatal development. Multiple congenital anomalies can prompt microarray testing for an underlying chromosome imbalance.

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