Neonatal and paediatric genetics centres around the diagnostic investigation of developmental delays, autism spectrum disorder, learning difficulties, and where there are clinical indications of congenital anomalies. 

 

As with pre-natal cytogenetics, there are a number of techniques that can be used, depending on the clinical condition under investigation. All can be performed on a blood sample.

Conventional chromosome testing is the applicable for the investigation of syndromes such as Down syndrome, Turner Syndrome and reproductive health.

Conventional cytogenetic analysis involves the analysis of the whole genome at the cellular level to detect large genomic changes and chromosomal rearrangements. This test involves culturing white blood cells to produce metaphase spreads of chromosomes, from which slides are prepared and representative cells are captured into digital images.

Test NameChromosomes Blood
Clinical IndicationFor investigation of:
1. For the investigation of Down and Turner Syndrome
2. Follow up testing by conventional analysis
3. Parental and family studies
Gene(s)All Chromosomes
MethodConventional chromosome analysis
Turn around time35 days
Medicare Eligibility73289
Sample TypeBlood
Collection Type10mL Lithium Heparin; For Difficult/Paediatric Collect: Min 1mL
Special InstructionsTransport cooled or at room temperature

Chromosome microarray (also known as molecular karyotyping) is the gold standard for the diagnostic investigation of autism spectrum disorder, learning difficulty, developmental delay and where there are clinical indications of congenital anomalies. This is an advanced genome-wide investigation used to detect sub-microscopic detect loss and/or gain of DNA that are associated with microdeletion and microduplication syndromes but are not readily detectable by conventional karyotype and/or fluorescence in-situ hybridisation (FISH).

Test NameChromosomal Microarray- Blood
Clinical IndicationFor the first line investigation of intellectual disability, developmental delay, autism, or in the presence of at least two congenital abnormalities.
Gene(s)Genome-wide
MethodChromosomal Microarray
Turn around time4 -6 weeks
Medicare Eligibility73292– Criteria applies
Sample TypeBlood
Collection TypeBlood: 6mL in EDTA tube
Newborn to 12 months: 1mL in paediatric EDTA tube
Special InstructionsRequest ‘Chromosomal Microarray’ on referral form. Clinical details required.

Fluorescence in-situ hybridisation (FISH) is a targeted molecular cytogenetic technique used for the investigation of specific chromosome regions involved in the particular syndrome. The technique binds a colour labelled DNA probe to a specific region on the patient chromosomes.

As this is a targeted test it is important when requesting a FISH test to indicate the clinical condition that is being tested for.

Test NameFISH Blood
Clinical IndicationFor neonatal diagnosis of suspected chromosomal syndromes
Gene(s)Chromosomes X and 21
MethodFISH
Turn around time2 days
Medicare Eligibility73291
Sample TypeBlood Paediatric Collect
Collection TypeMin 1mL in 1 x Lithium heparin tube
Special InstructionsNo additional sample required. Test is performedwith chromosome analysis

Specific Microdeletion Probes

Syndrome/IndicationChromosome locationGene
1p36 microdeletion1p telomere/1p36Genes at 1p36
WOLF-HIRSCHHORN4p16.3Genes at 4p
Cri du Chat5p15.2EGR1
Sotos5q31NSD1
Williams-Beuren7q11.23ELN
Prader Willi15q11-q13Genes at 15q11.2-q13
Angelman15q11-q13Genes at 15q11.2-q14
Smith-Magenis17p11.2RAR1
Miller-Dieker17p13.3LIS1
Di George/VCFS22q11.2Genes at 22q11.2
22q microdeletion syndrome22q13.3Genes at 22q13
X inactivationXq13.2XIST
Xp Yp deletionsXp and YpSHOX
Yp rearrangementsYp11.3SRY
ACRO P = Acrocentric p-armsAll sub-telomere probes 
All chromosomesp-arms acrocentrics 
All chromosomesWhole chromosome paints 
Test Name FISH Blood
Clinical Indication For neonatal diagnosis of suspected chromosomal syndromes
Gene(s) Chromosomes X and 21
Method FISH
Turn around time 2 days
Medicare Eligibility 73291
Sample Type Blood Paediatric Collect
Collection Type Minimum 1mL in 1 x Lithium heparin tube
Special Instructions No additional sample required. Test is performed with chromosome analysis

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