Neonatal/Paediatric Genetic Tests

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 Name Chromosomes Blood
Clinical Indication

For 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) Chromosomal Analysis
Method Conventional chromosome analysis
Turn Around Time 35 days
Medicare Eligibility 73289
Sample Type Blood
Collection Type 10mL Lithium Heparin; For Difficult/Paediatric Collect: Min 1mL
Special Instructions Transport 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 Name

Chromosomal Microarray- Blood

Clinical Indication

For the first line investigation of intellectual disability, developmental delay, autism, or in the presence of at least two congenital abnormalities.

Gene(s)

Genome-wide

Method

Chromosomal Microarray

Turn Around Time

4 - 6 Weeks

Medicare Eligibility

73292- Criteria applies

Sample Type

Blood

Collection Requirements

Blood: 6ml in EDTA tube
Newborn to 12 months: 1ml in paediatric EDTA tube

Special Instructions

Request ‘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 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 Min 1mL in 1 x Lithium heparin tube
Special Instructions No additional sample required. Test is performedwith chromosome analysis

 

Specific Microdeletion Probes

 

Syndrome/Indication Chromosome location Gene
1p36 microdeletion  1p telomere/1p36 Genes at 1p36
WOLF-HIRSCHHORN 4p16.3 Genes at 4p
Cri du Chat 5p15.2 EGR1
Sotos 5q31 NSD1
Williams-Beuren 7q11.23 ELN
Prader Willi 15q11-q13 Genes at 15q11.2-q13
Angelman 15q11-q13 Genes at 15q11.2-q14
Smith-Magenis 17p11.2 RAR1
Miller-Dieker 17p13.3 LIS1
Di George/VCFS 22q11.2 Genes at 22q11.2
22q microdeletion syndrome 22q13.3 Genes at 22q13
X inactivation Xq13.2 XIST
Xp Yp deletions Xp and Yp SHOX
Yp rearrangements Yp11.3 SRY
ACRO P = Acrocentric p-arms All sub-telomere probes  
All chromosomes p-arms acrocentrics  
All chromosomes Whole chromosome paints  

Gilbert Syndrome is characterised by jaundice due to increased levels of unconjugated plasma bilirubin. Men are at higher risk than females and usually present post-puberty. In people of northern European ancestry, cases of Gilbert Syndrome are often associated with inheriting two copies (one from each parent) of a specific mutation in the promoter region of the gene encoding the enzyme glucuronyltransferase (UGT1A1), designated UGT1A1*28 allele. UGT1A1 is a liver enzyme important for clearing conjugated bilirubin from the circulation. In general, other than the low grade elevated bilirubin levels, people with Gilbert Syndrome exhibit no other signs or symptoms.

Testing for Gilbert Syndrome may assist in differentiating the cause of isolated elevated bilirubin levels in those patients with normal test results for FBC, reticulocytes, haptoglobin and liver enzymes.

 

Test Name

Gilbert’s Syndrome Genotyping

Clinical Indication

  1. For the investigation of hyperbilirubinaemia (jaundice)
  2. To determine greater susceptibility to irinotecan induced gastrointestinal and bone marrow toxicity

Gene(s)

UGT1A1 (UDP-glucuronosyltransferase Family 1 Member A1)

Method

PCR Genotyping

Turn Around Time

28 days

Medicare Eligibility

No

Medicare Descriptor

N/A

Sample Type

Blood

Collection Type

10mL EDTA tube

Special Instructions

None