Genetic Carrier Screening

Gene Access

The Clinical Labs Gene Access Genetic Carrier Screening test provides patients with information regarding their chances of having a child with cystic fibrosis (CF), spinal muscular atrophy (SMA), or fragile X syndrome (FXS).

• One in 20 individuals are carriers of at least one of these conditions;
• 90% of carriers do not have a family history;
• One in 160 couples will be found to be at risk of having an affected child.
   

CYSTIC FIBROSIS (CF)

Approximately 1 in 25 individuals are carriers of CF. Clinical Labs’ CF screening covers more than 75 common mutations in the CFTR gene. CF affects approximately 1 in 2,500 individuals and is a severe autosomal recessive genetic condition that causes lung and gastrointestinal problems.

SPINAL MUSCULAR ATROPHY (SMA)

SMA is an autosomal recessive inherited neuromuscular disease historically associated with high morbidity and mortality. Approximately 1 in 35 people are carriers of SMA. Clinical Labs’ SMA screening identifies deletions of the SMN1 gene (one copy), which account for approximately 96% of the mutations in this gene. SMA affects approximately 1 in 6,000 people.

FRAGILE X SYNDROME (FXS)

FXS, an X-linked condition, is the most common inherited form of intellectual disability, affecting approximately 1 in 3,600 men and 1 in 6,000 women. Approximately 1 in 330 people are carriers of FXS. 

FXS carrier screening is recommended for females, as it is inherited in a different way to CF and SMA. Female patients who have the gene change (number of CGG triplet repeats) in the FMR1 gene are found to be at risk of having a child affected by FXS, as the abnormal gene may expand over generations. The size of these CGG triplet repeats determines the chance of the FXS gene failing to function in a normal way and, therefore, the clinical presentation. Males can also carry the faulty FMR1 gene on their one X chromosome and may pass it on to their daughters. (Testing would incur a private fee - not eligible for Medicare billing). 
 

Genetic Carrier Screening should be offered to every woman or couple

Australian clinical guidelines (RANZCOG & RACGP)^1,2 recommend that doctors offer genetic carrier screening to every woman and couple who are planning or in the first stage of pregnancy, regardless of their risk factors.

Ideally, screening is performed prior to conception to offer greater reproductive choice. Early detection is paramount as it allows more time for counselling and provides greater reproductive options for those at risk. With carrier screening for CF, SMA, and FXS being Medicare-rebatable, testing can be offered earlier during routine appointments, alongside other prenatal screening tests.

<sup>1. The Royal Australian and New Zealand College of Obstetricians and Gynaecologists (RANZCOG) Guidelines. 
2. The Royal Australian College of General Practitioners (RACGP) Guidelines.</sup>
 

Medicare Eligibility Criteria

Bulk-billed genetic carrier screening is now available to determine a couple’s combined risk of having a child with a genetic condition. Testing is available for all individuals, even those with no symptoms or family history. Male partners of the biologically female positive cases for CF or SMA (not FXS) are eligible for testing under Medicare cover. Please see below for specific Medicare criteria. Private fee may apply if criteria are not met.

New items 73451 and 73452 

The patient who is planning pregnancy or already pregnant should be tested first under MBS item 73451 prior to testing the reproductive partner patient under MBS item 73452 to ensure an informative and clinically relevant test result is obtained in the relevant gene.

73451 

Testing of a patient who is pregnant or planning pregnancy to identify carrier status for pathogenic or likely pathogenic variants in the following genes, for the purpose of determining reproductive risk of cystic fibrosis, spinal muscular atrophy, or fragile X syndrome: 

a.    CFTR; 
b.    SMN1; 
c.    FMR1.

One test per lifetime. 

The intent of MBS item 73451 is to test an asymptomatic female chromosomal sex patient who is either planning a pregnancy or is already pregnant. 

73452

Testing of the reproductive partner of a patient who has been found to be a carrier of a pathogenic or likely pathogenic variant in the CFTR or SMN1 gene identified by testing under item 73451, for the purpose of determining the couple’s reproductive risk of cystic fibrosis or spinal muscular atrophy. 

One test per condition per lifetime. 

The intent of MBS item 73452 is to test an asymptomatic male chromosomal sex patient who is the reproductive partner of the patient planning pregnancy or already pregnant and has been tested under item 73451.