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Short Description : Whole genome microarray
Also known as : [Molecular Karyotype]

Test performed by: LabPLUS Diagnostic Genetics

Update of Referral Criteria for Molecular karyotype testing

The vast majority of referrals for the molecular testing of DNA from children with learning difficulties, intellectual disability and/or autism ask for BOTH Fragile X syndrome testing and a molecular karyotype (also known as microarray testing) . In conjunction with the Genetic Health Service of New Zealand (Northern Hub), we have made a commitment to ensure that this testing  undertaken appropriately.

From 1st November 2015: All routine requests for both microarray and Fragile-X tests will be tested by microarray in the first instance (refer Fragile X test page).  Please also refer to the Diagnostic Use and Interpretation section below for a recommended testing pathway for these types of referrals.

Specimen Collection
EDTA4 mL Adult EDTA Blood
EDTA0.5 mL Paediatric EDTA Blood
Sterile Container% Adult Sterile Container Tissue

Please note : Any Molecular Karyotype(Array) requests on non- blood samples register as DGEN

Turnaround Time: Between 2 weeks and 4 weeks

There are delays in TAT for non-urgent postnatal referrals. If you have not received a result within the stated TAT, and the results if required for clinical management, please contact the laboratory at microarray@adhb.govt.nz so that we can expedite analysis.

Contact Information

Contact the Cytogenetics Laboratory via: LabLink ext 22000, or via email: microarrary@adhb.govt.nz

Specimen Transport Instructions for Referring Laboratories

Transport at room temperature. If necessary specimens can be stored refrigerated overnight for transport  at room temperature the following day.

Download: Link to: - Microarray Info for Medical Staff.pdf

Download: Link to: - Microarray Info for Patient and Parents.pdf

Diagnostic Use and Interpretation:

Microarray-based testing screens for genomic imbalance (chromosomal losses and gains) across the entire human genome at a significantly higher genomic resolution (and consequentially higher diagnostic yield) than standard cytogenetic chromosome analysis. However since this technology has limitations; it is currently only best practice for use in the investigation of patients with specific diagnostic criteria i.e. unexplained multiple congenital anomalies (MCA), developmental delay/intellectual disability (DD/ID) and autism spectrum disorders (ASD) [ Best Practice Microarray Analysis Guidelines for Australasian Laboratories, Australasian Society of Cytogeneticists, ASoC-QAL-I001]).

Compared to standard cytogenetic chromosome analysis this technique is unable to detect balanced rearrangements and low level mosaicism of unbalanced rearrangements/aneuploidy. Also, unlike FISH, it cannot be done as a rapid test. Therefore this test should not be used with a family history of a balanced chromosomal rearrangement, couples experiencing infertility/multiple spontaneous pregnancy losses, suspected mosaicism, or patients with a recognizable syndrome where a more rapid test is available.

Download: : - LabPLUS GHSNZ Genetic Testing Pathway for DD ID MCA ASD.jpg

Download: : - LabPLUS Genetic Testing Criteria for Neonates.jpg

  ADHB Newborn Services Clinical Guidelines

Please Note: the microarray platform currently being used contains single nucleotide polymorphism (SNP) probes that can detect (in addition to copy number gains and losses) Long Contiguous Stretches of Homozygosity (LCSH). The detection of LCSH may indicate homodisomic uniparental disomy (UPD), identity by descent, or loss of heterozygosity (LOH). However, SNP probes cannot detect heterodisomic uniparental disomy and current guidelines recommend confirmation of UPD by haplotype analysis (CCMG Guidelines for Genomic Microarray Testing July 13, 2010).

Last updated at 16:35:48 09/09/2021