Medical Genetics Test Details
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|Expanded Chromosomal Microarray Analysis - Prenatal - Amniotic Fluid|
|Test Information:||CMA-Expanded utilizes array-based comparative genomic hybridization (aCGH) and contains 400,000 oligonucleotides for copy number analysis and SNP probes for all chromosomes for detection of uniparental disomy (UPD) and consanguinity. SNP probes are also useful for for the detection of triploidy. This expanded prenatal array offers exon-by-exon coverage of over 1,700 genes. It is recommended for providers and patients who want the highest level of detection possible. This option may be the best choice for fetal evaluations assessing possible copy number changes at breakpoints of de novo apparently balanced rearrangements. CMA is limited to detection of gains and losses of genomic material and will not detect low-level mosaicism, balanced translocations, inversions or point mutations in specific genes.
Product of Conception(POC) tests should be requested using the Cytogenetics - Products of Conception Requisition
Prenatal CMA Procedures and Reporting Guidelines 2/2012
Parental Samples (5 cc whole blood in EDTA tubes) are required.
Signed CMA consent is recommended.
Cultured fetal specimens >3 weeks old may yield uninterpretable results.
Maternal Cell Contamination studies will be performed in all cases
For appropriate fetal copy number changes, parental CMA studies will be performed to help clarify the significance of the fetal results
The following copy number changes will not be reported based on information available at reporting:
Gains and Losses less than 1000 kb (1Mb) without any genes in the region
Gains less than 500kb with genes but no known clinical relevance
Gains of KAL1, 15q11.2 BP1-BP2, NPHP1, STS
Gains and Losses in the Mitochondrial Genome
Gains and Losses in AZFa & AZFb
Gains and Losses associated with adult-onset disorders for which treatment is unavailable
Parental Studies will not be performed for the following fetal results:
Heterozygous Gains and Losses in genes associated with autosomal recessive disorders
Heterozygous Gains or Losses in a female fetus of genes associated with X-linked recessive disorders
For a comprehensive disorder list, please see the Prenatal Chromosomal Microarray Analysis - Standard Resolution Disorder Table.
Additional Testing Recommendations for Absence of Heterozygosity (AOH) detected on Prenatal Chromosomal Microarray analysis (CMA):
Single chromosome AOH is associated with germ-line or somatic uniparental disomy. Knowledge of UPD is of clinical relevance depending on the chromosome involved.
Uniparental disomy (UPD) is the inheritance of two chromosomes or chromosomal regions from only one parent. UPD of imprinted genes results in abnormal gene transcription resulting in an abnormal phenotype. There are well-established single chromosome UPD syndromes. UPD of a non-imprinted chromosomal region may be of no clinical significance save instances of an autosomal recessive mutation.
Effective immediately MGL will offer UPD analysis at no additional charge for regions of AOH of imprinted chromosomes (6, 7, 11, 14, & 15). MGL will alert the client of the AOH result and UPD testing recommendations; at which point the client may decline additional testing. If UPD testing is elected, parental EDTA blood or extracted DNA samples are required for fetal UPD analysis. MGL will work with your office to ensure parental samples are available. The turnaround time for UPD analysis is between 3-4 weeks and results will be reported in an updated CMA report. UPD analysis of non-imprinted chromosomes is available at charge. MGL will coordinate testing upon request from the client.
|Sample & Shipping Information|
|Test Requisition:||Prenatal CMA and Cytogenetics|
|Specimen Type:||Specimen Information|
|Shipping Conditions:||Ship at ambient temperature in an insulated container by overnight courier.
|Turn Around Time:||14 days. If direct sample is not satisfactory, cultured cells will be used and the turnaround time will be longer.|
|List Price:||*For Insurance or Institutional Prices, please call.|
|CPT Codes:||81229x1, 81265x1, and 81266x1|