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Microarray Analysis - Solid Tissue (Product of Conception)
Also known as : [Chromosome Analysis - Solid Tissue (Non-Tumour)]


Chromosome Analysis
Test performed by: LabPLUS - Dept. Diagnostic Genetics - Cytogenetics


Guideline for Referral

Microarray (molecular karyotype) analysis is undertaken on fetal and extra0fetal tissue samples where a chromosome abnormality is suspected.

G-banded karyotype analysis (chromosomes) is not routinely performed, as microarray replaces conventional karyotype analysis for this referral type.

It is essential to provide the following information when referring a sample:

  1. Gestational age
  2. Suspected disorder/diagnosis
  3. List of all symptoms/phenotypes directly relevant to the suspected diagnosis
  4. Explanation of family history (if present)
  5. NHI or lab number of previously tested family members (if applicable)

Turnaround Time: 6 weeks.

If you have not received a result within the stated TAT, and the result is required for clinical management, please contact the laboratory at microarray@adhb.govt.nz to expedite the analysis.

 

Samples prior to 20 weeks gestation:

History of recurrent miscarriage (3rd consecutive miscarriage)

Abnormalities detected on ultrasound, or at post-mortem, congenital abnormalities, in-uterine growth restriction, fetal loss following abnormal maternal serum screen test.

Known familial chromosomal rearrangement,

Confirmation of other prenatal testing (e.g. non-invasive prenatal testing).

 

Samples 20 weeks gestation or later:

In-uterine death (IUD), stillbirth, neonatal death (NND).

Abnormalities detected on ultrasound, or at post-mortem, congenital abnormalities, intra-uterine growth restriction, fetal loss following an abnormal maternal serum screen test.

Known familial rearrangement.

Confirmation of other prenatal testing (e.g. non-invasive prenatal testing).

 

Samples received with no/insufficient clinical information or clinical details not meeting the referral criteria will not be fully processed for microarray analysis.

Referring clinicians will be informed, in writing, that these samples will be stored for 6 months and analysis can be undertaken if appropriate clinical information is provided.

Samples will be disposed of in accordance with laboratory policy after 6 months from date of receipt.


Specimen Collection

Minimum sample size: 5mm 3

Solid Tissue: Placenta, cord and skin are all suitable for analysis. Where possible please send two or more types of tissue.

Tissue should be placed in a sterile container with transport media (provided by the Cytogenetics Laboratory). If this type of container is not available, place the specimen in sterile saline. Please do not send the specimen dry. Specimens should be as fresh as possible and kept at ambient temperature.


Fibroblast culture

We also provide a fibroblast culture service, where tissue samples can be grown for other (non-cytogenetic) tests, or long-term storage.

Prenatal skin specimens and those from live-born babies, children and adults, are accepted for both karyotyping and for a variety of molecular and metabolic tests, either performed at LabPlus or in another laboratory. We will prepare the specimen for sending to the appropriate laboratory and/or provide storage in liquid nitrogen for future testing.

Cultures requiring sendaway for further testing should be accompanied with a fully complete LabPlus Genetic Sendaway Test Request Form. See the Diagnostic Genetics Sendaway Service Information Page.

Download: Download: - Diagnostic Genetics Sendaway Form -June 2019 .docx


Assay Method

Majority of samples will be analysed using a microarray method. This approach gives a higher resolution and greater success rates compared to other methods. 

Array platform used: CytoScan Optima Array and Affymetrix Chromosome Analysis Suite (ChAS) v3/na33.

Experimental details and limitations:

i) This platform has a minimum resolution for copy-number detection of 1 Mb for losses, 2 Mb for gains, with increased resolution to at least 200 kb for selected gains. Losses smaller than 1 Mb or gains smaller than 2 Mb will not be reported unless associated with a gene/region of known pathogenicity. Heterozygous carrier status for recessive conditions is not routinely reported.

ii) Regions of homozygosity (ROH) are not reported, however this data is retained by the laboratory.

iii) Where a normal female karyotype is reported, using tissue from products of conception, there is a slight chance that is has been obtained from DNA of maternal origin.

iv) Microarray analysis will not detect balanced alterations, point mutations, imbalances of regions not represented on the microarray and may not detect low level mosaicism.

v) Agenic regions, well established polymorphisms and regions only containing non-coding / pseudogenes are not reported. Male Y chromosome changes are not reported except in cases of suspected aneuploidy.

vi) Interpretation is based on GRCh37 (hg19) human reference sequence. Nomenclature is according to ISCN (2020).


Contact Information

Results or General Enquiries : use ward computer or contact Lablink: ext 22000, DDI (09) 307-8995 or 0800 522 7587.

Other contacts:

Microarray: microarray@adhb.govt.nz ; ext. 22008

Microarray Section Leader: Karen Claxton

FISH and G-banded karyotype (chromosomes): cyto@adhb.govt.nz ; ext. 22008

Cytogenetics Acting Section Leader: Sarah Mitchell



Last updated at 11:36:14 13/10/2021