Sorted By Test Name - Mayo Medical Laboratories

CGH
88898
aCGH analysis in a patient and aiding in the clinical interpretation of the pathogenicity of the copy
number change.
Interpretation: An interpretive report will be provided.
Reference Values:
An interpretive report will be provided.
Clinical References: 1. Shaffer LG, Kashork CD, Saleki R, et al: Targeted genomic microarray
analysis for identification of chromosome abnormalities in 1500 consecutive clinical cases. J Pediatr 2006
Jul;149(1):98-102 2. Baldwin EL, Lee JY, Blake DM, et al: Enhanced detection of clinically relevant
genomic imbalances using a targeted plus whole genome oligonucleotide microarray. Genet Med 2008
May;10:415-429
Array Comparative Genomic Hybridization (aCGH), Whole
Genome, Constitutional
Clinical Information: Aneuploidy or unbalanced chromosome rearrangements are often found in
patients with mental retardation, developmental delay, autism, dysmorphic features, or multiple
congenital anomalies. Some pathogenic chromosome imbalances are large enough to be detected with
conventional chromosome analysis, however many pathogenic rearrangements are at or below the limits
of resolution of chromosome analysis (approximately 5 megabases). Array comparative genomic
hybridization (aCGH) is a method for detecting copy number differences (gains or losses) across the
entire genome in a single assay. This test provides a molecular karyotype and has a minimum functional
resolution of approximately 100 kilobases throughout the genome. In addition, higher resolution coverage
of targeted regions has a minimum functional resolution of approximately 20 kilobases. Targeted regions
include common microdeletion and microduplication syndromes, many genes involved in Mendelian
disorders, and the pericentromeric and subtelomeric regions of the genome. As a participant in the
International Standard Cytogenomic Array Consortium (ISCA), Mayo Clinic Cytogenetics Laboratory
contributes submitted clinical information and test results for molecular cytogenetic tests to a
HIPAA-compliant, de-identified public database hosted by the National Institute of Health. This is an
international effort to improve diagnostic testing and our understanding of the relationships between
genetic changes and clinical symptoms (for information about the database visit the consortium website at
https://isca.genetics.emory.edu). Confidentiality of each sample is maintained. Patients may request to
opt-out of this scientific effort by calling the laboratory at 1-800-533-1710, extension 8-2952 and asking
to speak with a laboratory genetic counselor. Please call with any questions.
Useful For: As a first-tier, postnatal test per the American College of Medical Genetics (ACMG)â€s
practice guidelines for individuals with multiple anomalies not specific to well-delineated genetic
syndromes, individuals with apparently nonsyndromic developmental delay or intellectual disability and
individuals with autism spectrum disorders. As an appropriate follow-up for individuals with unexplained
developmental delay/intellectual disability, autism spectrum disorders, or multiple congenital anomalies
with a previously normal conventional chromosome study due to the superior resolution of the
chromosomal microarray testing. Determining the size, precise breakpoints, and gene content, and
unveiling unappreciated complexity of abnormalities detected by other methods such as conventional
chromosome and FISH studies. Determining if apparently balanced abnormalities identified by previous
conventional chromosome studies have cryptic as a large proportion of such rearrangements appear
balanced at the resolution of a chromosome study, but may actually be unbalanced when analyzed by
higher-resolution chromosomal microarray.
Interpretation: When interpreting results, the following factors need to be considered: -Copy number
variation is found in patients with abnormal phenotypes and benign variations are found in all individuals.
Therefore the differentiation between pathogenic and benign copy number variation can be challenging.
-While most copy number variations observed through chromosomal microarray testing can readily be
characterized as pathogenic or benign, a subset have limited data available to support classification into
either of these categories. In these situations, a number of considerations must be taken into account to
help interpret the data, such as the nature of the imbalance, the size and gene content of the interval, mode
of inheritance, and the presence of the variation in a parent. -The continual discovery of novel copy
Current as of January 4, 2013 7:15 pm CST 800-533-1710 or 507-266-5700 or MayoMedicalLaboratories.com Page 175