Medicare rebates for genetic testing of
paediatric private patients
Introduction
Genetic abnormalities which cause disease
can be chromosome-level ‘structural’ changes
that may involve dozens to hundreds of genes.
Alternatively, they can be changes at the level of a
single gene of interest.
Testing for genetic abnormalities can be useful
in paediatric practice, especially in the diagnosis
of developmental delay. However, the majority of
‘genetic’ tests are not rebated by Medicare. There
is, however a Medicare Benefits Schedule (MBS)
item number for microarray testing, and it may be
useful to briefly summarise the current situation
regarding rebates for genetic testing of private
patients.
Large scale/chromosomal genetic testing
Large structural variants involving many genes
– such as deletions, duplications, aneuploidies,
translocations and inversions – can be detected
by karyotype analysis, which looks at all 23 pairs
of chromosomes at the same time. There is an
MBS rebate for karyotype testing (Item 73289),
which covers most of the cost of this test, with a
gap payment covering the remainder.
Some specific syndromes, such as DiGeorge
syndrome/22q11.2 deletion syndrome and
Williams syndrome, are caused by smaller
deletions or duplications. These are sometimes
called ‘microdeletions’ and ‘microduplications’,
as they can be difficult to see by conventional
karyotype, although they may still involve many
genes. Deletions or duplications of these regions
can be detected by specific targeted methods,
including FISH (fluorescence in-situ hybridisation)
and MLPA (multiplex ligation-dependent probe
amplification). There is an MBS rebate item for
testing for these microdeletions/duplications in
some circumstances (Item 73291). This rebate
covers most of the cost of such tests, but only
applies to patients ‘with developmental delay,
intellectual disability, autism or at least two
congenital abnormalities,’ or relatives of such
patients. It is therefore important to note all
relevant clinical details on the test request form.
Microarray testing is similar to karyotype in that
it looks at changes in all chromosomes at the
same time. While it cannot detect ‘balanced’
changes (like translocations), it can detect
much smaller deletions and duplications than
karyotype, including most microduplications
and microdeletions such as those mentioned
above. For this reason, microarrays have a higher
diagnostic yield than karyotype in patients
with non-syndromic developmental delay.
There is an MBS rebate for microarray testing
(Item 73292) which covers most of the cost
of this test. However, this rebate item has two
main conditions. Firstly, if microarray testing is
performed on the same ‘episode’ (same blood
test) as a karyotype or a FISH/MLPA test, the
microarray is the only test that can be rebated for
that episode. Secondly, for microarray testing to
be rebated, the patient must have ‘developmental
delay, intellectual disability, autism or at least two
congenital abnormalities.’
This means that if an array test is ordered on
the same blood sample as a karyotype and/or a
specific microdeletion/duplication test, there will
be a significant cost to the patient for the other
test(s). This does not apply if the tests are ordered
on separate episodes, i.e. on blood samples
drawn on different days.
Single gene testing
‘Mendelian’ or single-gene disorders are caused
by mutations in a specific gene. These are the
classic autosomal dominant, recessive or X-linked
disorders, such as Fragile X syndrome or cystic
fibrosis. Microarray testing can occasionally
detect Mendelian disorders when one of the
genes within a microdeletion or duplication is
involved in a Mendelian syndrome. However,
smaller mutations (such as point mutations and
triplet repeat expansions) underlie most singlegene disorders, and these mutations will not be
detected by microarray testing.
For this reason, if a single-gene disorder is
suspected, a specific test will need to be
carried out to examine that gene. This is often a
sendaway test to a specialist referral laboratory.
There are MBS item numbers for only a very
limited range of single gene disorders.
Of disorders particularly relevant to paediatric
practice, Fragile X syndrome is currently the
only one that is rebated by Medicare (MBS Items
73300 and 73305). The rebate for Fragile X
testing only applies if the patient has intellectual
disability/developmental delay.
Summary
The ‘first line’ genetic tests for patients with nonsyndromic developmental delay are currently
microarray testing and Fragile X testing. Both
of these have MBS item numbers (for patients
that meet the criteria), and their rebates are not
mutually exclusive.
Karyotype and specific microdeletion/duplication
testing will be rebated (for patients that meet the
criteria), but only if it is not on the same episode as
an array test.
If a single-gene disorder other than Fragile X is
suspected, there is unlikely to be a rebate. In these
cases, it may be useful to discuss testing with the
laboratory and/or a clinical genetics service.
Dr James Harraway FRCPA
Dr Harraway completed his medical training in Christchurch, New Zealand. In 2005, James was awarded a Nuffield Medical
Fellowship to undertake a DPhil at Oxford University, examining the molecular pathogenesis of Cockayne syndrome. In 2008,
he became the first pathologist from New Zealand to obtain an FRCPA in genetic pathology.
Dr Harraway is available for consultation.
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