Information for Health Professionals
Microarray analysis is a DNA-based method of genetic
analysis, which can identify clinically significant chromosome abnormalities
that are below the resolution of conventional chromosome analysis.
Microarray analysis can be performed on prenatal diagnostic samples, peripheral
blood, and products of conception.
does chromosome microarray analysis work?
DNA from the sample is prepared and hybridized to a glass slide, on
which a large number of molecular probes are arrayed; these probes consist
of small segments of DNA corresponding to clinically significant (and potentially
significant) regions covering the entire genome. Currently available
microarrays contain more than two million unique DNA probes. Computerized
analysis of the hybridization pattern on the slide reveals the number of
copies of DNA corresponding to each probe location. Therefore, this
analysis is able to diagnose deletions and duplications of whole chromosomes,
portions of chromosomes, and specific locations where copy number variants
(CNVs) are associated with particular genetic diseases.
types of disorders can chromosome microarray analysis diagnose?
are some other important points?
cause for a pregnancy loss, even when fetal tissue or products of conception
does not contain viable cells
The basis for
fetal anomalies detected by ultrasound, when conventional chromosome analysis
on a prenatal diagnosis sample was normal
A genetic etiology
for an infant, child, or adult who has mental retardation, with or without
physical abnormalities and/or birth defects
or microduplication syndromes that would not be detected on a routine prenatal
for chromosome microarray analysis?
detects unbalanced, but not balanced, chromosome abnormalities. Thus,
blood chromosome analysis for both members of a couple having recurrent
pregnancy loss is still important.
With some types
of microarrays, additional genetic information can be obtained, including
suspected consanguinity or uniparental disomy.
does not identify all genetic disorders. For instance, it does not
detect sequence variation (e.g., point mutations), a major cause of dominant,
recessive, and X-linked disorders.
Hundreds of small
chromosome deletions and duplications are found in everyone; hence, the
clinical significance of some CNVs identified by microarray analysis cannot
be determined. Parental microarray studies are sometimes necessary
to properly interpret those "variants of uncertain clinical significance";
however, even then, the clinical significance of some abnormal results
Genetic consultation can be helpful in
ordering and interpreting microarray analysis, and may also identify an
indication for additional genetic testing, based on clinical findings and
family history, when determining a diagnosis.
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This page last updated on February