Current UK screening

The newborn and 6-8 week infant physical examinations

Mothers of all infants are offered two screening physical examinations of their babies within the first 72 hours of birth and at 6-8 weeks of age. Like the mid-pregnancy ultrasound scan, this is a general examination which can detect a wide range of physical problems. But the following specific aspects of the examination are part of the screening programme and subject to pathway standards. This is used to screen for:

• Congenital cataracts - by ophthalmoscope examination.
• Congenital heart disease - by examination of the cardiovascular system.
• Undescended testes - by palpation of the scrotum and inguinal canals.
• Developmental dysplasia of the hip - by the Barlow and Ortolani tests and examination of the lower limbs for asymmetry or limited abduction.

Newborn hearing screening

Parents are offered a hearing screen for their baby within 4 to 5 weeks of birth. The screen is usually carried out before discharge from hospital, but in some areas it is carried out in the home.

The first test offered is the Automated Oto-acoustic Emission (AOAE) screening test. This involves placing a soft-tipped probe into the baby's ears, playing sounds and trying to detect a response - 'echo' - from the baby's cochlea.

Well babies who do not have a clear response to this test, (this is called a 'no clear response'), have a second screening test before referral. This may be a repeat AOAE at home or in a local clinic or an Automated Auditory Brainstem Response (AABR) screening test.

AABR involves playing sounds to the baby and trying to detect responses from their brainstem via electrodes placed on the baby's head and neck.

Babies who have spent more than 48 hours in a Neonatal Intensive Care Unit (NICU) or Special Care Baby Unit (SCBU) are regarded as high risk and are screened using both AOAE and AABR, except in Wales and some areas of Scotland where they are screened using AABR only.

Any baby referred from the Newborn Hearing Screen should be seen for full audiological assessment within four weeks of screen completion.

Newborn blood spot screening

Mothers of all newborn babies are offered testing for the following conditions by testing a blood spot taken from the baby (often referred to as the 'heel prick' and previously known as the 'Guthrie' test) at 5-8 days of life (ideally on day 5). For many of these disorders early detection can be critical.

• Phenylketonuria (PKU):
  • Incidence 1:12,000.^[2][3]
  • Current tests look for a combination of total biopterin and dihydropteridine reductase from neonatal blood spots.
  • The original 'Guthrie' test (semi-quantitative and difficult to automate) is being gradually superseded by chromatography, fluorometry or mass spectrometry.
  • Early diagnosis and treatment reduce the risk of neurological handicap from 80-90% to 6-8% (population baseline risk 2%).^[4]
• Congenital hypothyroidism:
  • Incidence is approximately 1:3,000.^[5]
  • Currently established on the same heel prick sample as above.
  • From April 1st, 2012 babies born at less than 32 weeks gestation (less than or equal to 31+6 days) will need a repeat test. The repeat test should be done at 28 days postnatal age, counting date of birth as day 0, or the date of discharge home, whichever is the sooner.
• Sickle cell disease:
  • Universal laboratory screening has been offered since 2005.
  • The form of screening for haemoglobin variants depends on the prevalence of the condition.
  • The programme allows the offer of sickle cell screening to all infants as an integral part of the newborn blood spot screening.^[6]
• Cystic fibrosis (CF):
  • 1 in 2,500 babies born in the UK have CF.^[7]
  • The carrier rate is 1 in 25.
  • Incidence varies around the country.
  • Biochemical screening is now universal. Initial screening detects raised levels of immunoreactive trypsinogen (IRT), which is then followed by DNA analysis.
  • The most common mutation is in the DF508 gene in 95% of affected individuals in the UK.
• Medium-chain acyl CoA dehydrogenase (MCAD) deficiency:
  • The estimated incidence is 1:8,000-1:15,000.^[8]
  • After a pilot study in six UK centres (screening more than 700,000 babies) this became part of the blood spot test from 2009.
• UK variation exists within the blood spot: in Northern Ireland and Wales sickle cell is not tested for and MCAD deficiency is not tested for in Wales at present, the introduction of above planned for 2012.
• Duchenne muscular dystrophy (DMD) is offered to newborn boys in Wales as part of the blood spot test.
• Parents can decline one or all of the tests included on the blood spot.

Possibilities for future screening programmes

The UK National Screening Committee (UK NSC) has over a hundred screening policies on conditions ranging from anaemia in pregnancy to vision in adults. Sometimes the UK NSC will recommend that screening for a condition should be offered and other times that, based on the current available evidence, screening should not be offered.

All the policies are available in the UK NSC's policy database.

New evidence from research is being published all the time and it might be that, even if screening for a condition could not be recommended in the past, new evidence suggests otherwise. This means that it is important for the UK NSC to review all its policies on a regular basis.

The following are not currently recommended by UK NSC, but available in some countries.
The strongest cases can be made for screening for the following, although tandem mass spectrometry needs to be widely available:

• Glutaric aciduria type 1 (GA1) - estimated incidence 1:40,000.^[9][10]
• Galactosaemia (incidence 1:44,000), although neonatal mortality can be reduced with screening and early detection; long-term outcome is still poor.^[11]
• Biliary atresia - population screening using heel prick blood tests is not discriminatory enough.^[12]

Others include:

• Biotinidase deficiency:
  • The incidence is approximately 1:110,000-160,000.^[13]
  • It can be identified via blood spot analysis; hence, it would be straightforward to implement, and dietary supplementation prevents neurological deficit; however, UK incidence is currently thought to be too low to justify nationwide screening.
• Congenital adrenal hyperplasia (CAH):
  • The incidence is 1:17,000.^[14]
  • It is caused by 21-hydroxylase deficiency.
  • Screening has been shown to be beneficial in other countries.
• Disorders of organic acid and fatty acid metabolism:
  • These are rare and diverse recessively inherited conditions, some of which may be candidates for screening in the future.^[1]

The modified Wilson's criteria above are not currently met for the following conditions; hence, they are not recommended by the UK NSC:

• Non-PKU amino acidopathies - for example, tyrosinaemia type 1, homocystinuria and maple syrup urine disease.^[15]
• Familial hypercholesterolaemia.
• Other metabolic disorders - for example, peroxisomal, lysosomal, purine or pyrimidine, urea cycle or trace metal disorders.^[1]