Common Metabolic and Genetic TestsIn the UK, all newborn babies are routinely screened, by heel prick bloodspot testing early in life. In the UK 95% of babies are expected to have had a heel prick blood sample collected by day 8 after birth. All regions in England screen babies for three important metabolic and genetic defects. These are:
- Phenylketonuria (PKU)
- Congenital hypothyroidism (CH)
- Cystic fibrosis (CF)
Some English regions also now screen for one or more of the following conditions:
- Diseases associated with abnormal forms of haemoglobin in the blood, such as Sickle cell anaemia and thalassaemia
- Medium-chain acyl-CoA deficiency (MCADD)
These programmes are overseen by the UK Newborn Screening Committee (NSC). The NSC review the case for screening for other conditions, particularly in the light of new technology such as Tandem mass spectrometry screening (tandem MS), a technique that can detect blood markers which are associated with over 20 inherited metabolic disorders with just one test.
A Health Technology review concluded that tandem MS justifies the introduction of newborn screening for glutaric aciduria type 1 (GA1) and MCADD as therapeutic advances for these conditions may prevent a neurological handicap. A case could also be made for neonatal screening for congenital adrenal hyperplasia (CAH) which has been shown to be beneficial in other countries and for Biotinidase deficiency, which is of low incidence in the UK (estimated 1:100,000) though this may be outweighed by the simplicity of the screening methodology and the benefits in prevention of serious neurological disease. However, the accepted criteria for screening are not currently met for galactosaemia, tyrosinaemia type 1, homocystinuria and maple syrup urine disease, familial hypercholesterolaemia, peroxisomal disorders, urea cycle defects, trace metal disorders, purine or pyrimidine disorders, or lysosomal disorders.
Newborns who have certain symptoms or who are born to mothers who may have been exposed to certain pathogens may have a TORCH screen performed. TORCH is an abbreviation for the infections tested for and ie Toxoplasmosis, Other (including syphilis, varicella zoster and parvovirus), Rubella, Cytomegalovirus, and Herpes simplex virus. These infections are not serious for the mother but account for 2-3% of congenital disability.
