Genomics in general practice

Genetic tests and technologies

Newborn screening

Newborn screening

PRACTICE POINT

Screening is available to all newborns in Australia free of charge, and almost all babies are screened. There is a very small proportion of babies (1-2%) who may be lost to follow up or whose parents may refuse consent for screening. Depending on the condition, not all affected babies will be identified (eg only the most common variants causing cystic fibrosis [CF] are included in the screening test). Therefore, any suggestive symptoms in a child of a conditions included in newborn screening warrant further investigation by the general practitioner (GP). 

Depending on the program, GPs may or may not be notified of a positive screening result. Follow-up is usually handled by the screening program.

What do I need to know?

Screening can identify a number of rare but serious medical conditions, where early detection and intervention can reduce morbidity and mortality.

Traditionally, conditions included in the program are based on the ability of clinicians to intervene early to avoid death, disability or other harm. With the advancement of genetic technology, there is some interest in expanding newborn screening panels to include a wider range of conditions.

Newborn screening is optional in Australia, and research suggests participation is very high. Screening generally occurs two to three days after birth, and is usually arranged by midwives. In general, parents are not contacted when screening results are normal.

Less than 2% of babies tested require repeat or subsequent diagnostic testing. Screening programs in each state and territory are usually responsible for following up cases that require further testing. About one per 1000 (0.1%) babies tested will be diagnosed with a condition through newborn screening.

Refer to Table 1 for a list of conditions currently included in newborn screening programs in Australasia.

Table 1. Conditions screened in newborn screening programs in Australasia

Class

Condition

Amino acids

Argininaemia or arginase deficiency

 

Argininosuccinic aciduria

 

Citrullinaemia

 

Tyrosinaemia type 1

 

Homocystinuria

 

Maple syrup urine disease

 

Phenylketonuria

 

Pterin defects

 

Tyrosine aminotransferase deficiency

Organic acids

Beta-ketothiolase deficiency

 

Cobalamin C defect

 

Glutaric acidaemia type I

 

Holocarboxylase synthetase deficiency

 

3-hydroxy-3-methylglutaryl-CoA lyase (HMGCoA lyase) deficiency

 

Isobutyryl-CoA dehydrogenase deficiency

 

Isovaleric acidaemia

 

Methylmalonic acidurias

 

Propionic acidaemia

 

2-methylbutyryl-CoA dehydrogenase deficiency

 

3-methylglutaconyl-CoA hydratase deficiency

Fatty acid oxidation

Carnitine or acylcarnitine translocase deficiency

 

Carnitine transporter defect

 

Carnitine palmitoyl transferase I and II deficiency (CPTID, CPTIID)

 

3-hydroxy long chain acyl-CoA dehydrogenase deficiency (LCHADD)

 

Medium chain acyl-CoA dehydrogenase deficiency (MCADD)

 

Multiple acyl-CoA dehydrogenase deficiency (MADD)

 

Short chain hydroxy acyl-CoA dehydrogenase deficiency (SCHADD)

 

Trifunctional protein deficiency (TFPD)

 

Very long chain acyl-CoA dehydrogenase deficiency (VLCADD)

Other

Cystic fibrosis (CF)

 

Congenital hypothyroidism

 

Galactosaemia (not in Victoria)

Other considerations

In addition to the implications for a child diagnosed with an inherited condition, there are also implications for future pregnancies in the family (ie carrier parents, siblings of the carrier parents). Information about carrier screening Carrier screening is a test to determine whether an individual carries a genetic variant that does not generally affect that individual’s health, but increases his or her chance of having children with the condition in question. The outcome of such testing can influence future reproductive decisions. Carrier screening is performed on individuals who are not necessarily known to be at increased risk for a particular genetic condition. Screening tests can be conducted on individuals from specific groups such as those from a common ethnic background (eg: screening for Tay-Sachs disease carrier status in the Ashkenazi Jewish community) or entire populations. should be offered.

There are other disorders currently being considered including congenital adrenal hyperplasia (CAH), spinal muscular atrophy (SMA) and severe combined immune deficiency (SCID).

Further reading

Advertising