Guidance

7. Conditions

Updated 3 August 2018

1. Sickle cell disease

1.1 NHS sickle cell and thalassaemia screening programme

The NHS sickle cell and thalassaemia (SCT) screening programme is a linked antenatal and newborn programme that offers:

  • timely antenatal SCT screening to all women (and couples) to facilitate informed decision making
  • newborn screening for sickle cell disease (SCD) to achieve the lowest possible childhood death rate, and to minimise childhood morbidity from SCD

The SCT programme handbook provides information about SCT and all aspects of the screening programme.

1.2 Newborn screening for SCD

Newborn screening for SCD is part of the NHS newborn blood spot (NBS) screening programme.

About 1 in 2,800 babies born in the UK has SCD. SCD is the name for a group of related conditions which affect the quality of haemoglobin. Haemoglobin is carried in red blood cells, gives blood its red colour and is responsible for carrying oxygen around the body.

SCD is an autosomal recessive condition. This means that babies are only born with SCD if they inherit 2 faulty copies of the haemoglobin gene, one from each parent. There are different types of sickle cell disease because there are different types of unusual haemoglobin gene. The most common and most serious sickle cell disease is sickle cell anaemia.

People with SCD produce red blood cells which can change shape and become rigid when haemoglobin is de-oxygenated. Unusually shaped cells can block small blood vessels reducing the blood supply to that part of the body. These painful episodes, known as sickle cell crises, can be very severe and last up to a week. Although a crisis does not usually cause permanent damage, people with SCD are at an increased risk of serious infections, anaemia and a range of other problems including strokes and lung disease. Early intervention can minimise harm. Sickle cell disease is a serious and lifelong condition, but long term treatment can help manage many of the symptoms.

NBS screening also identifies people who are genetic carriers for SCD.

Further information on the condition, including symptoms and treatment, is available in the SCT programme handbook.

Information about newborn screening laboratory processes for SCD is available in the sickle cell and thalassaemia handbook for newborn laboratories.

1.3 Thalassaemia

The UK National Screening Committee (UK NSC) does not recommend newborn screening for thalassaemia. NBS screening for SCD does detect the most serious form of thalassaemia, beta thalassaemia major. It does not detect babies who are thalassaemia carriers.

2. Cystic fibrosis

About 1 in 2,500 babies born in the UK has cystic fibrosis (CF). CF is an autosomal recessive condition. This means that babies are only born with CF if they inherit 2 faulty copies of the gene involved, one from each parent. This gene is the CF transmembrane conductance regulator (CFTR) gene.

CF mainly affects the lungs and digestive system. Most faulty CFTR genes cause severe symptoms. A smaller number are associated with milder forms of CF.

Babies are only eligible for CF screening up to 8 weeks (56 days) of age. This is because the screening test is not reliable after this age.

2.1 Symptoms

Babies with CF have a problem transporting chloride across cell membranes, leading to thick secretions in the affected organs. They may not gain weight well and have frequent chest infections.

CF can affect the baby before birth. A small percentage of affected babies are born with blocked intestines, a condition called meconium ileus. About 70% of screen positive babies with CF show some symptoms by the time they have diagnostic tests. These can include problems absorbing food, as well as breathing difficulties. Eventually all patients with CF develop long term chest infections.

The abnormal transport of chloride in sweat glands leads to an increased level of chloride in the sweat of children with CF. This is the basis of the ‘sweat test’, which should always be used to investigate suspected cases and confirm a diagnosis.

2.2 Treatment

Treatment for babies with CF includes a high energy diet, medicines and physiotherapy. This treatment aims to:

  • improve nutrition by providing supplements containing enzymes to help digestion
  • reduce chest infections with frequent physiotherapy and antibiotics

Although children with CF may still become very ill, early treatment can help them live longer, healthier lives.

2.3 Identification of CF carriers

The screening test for CF may identify babies who are carriers of the CF gene, but the majority of carriers are not detected.

If a baby inherits 2 copies of the CF gene (one from each parent), they will have CF. If a baby inherits only one copy, they will not have CF but will be a carrier of the CF gene. Babies who are carriers do not require any treatment. More than 2 million people in the UK (about 1 in 25) are carriers of CF.

All parents who are notified that their baby is a carrier are advised to speak to their GP or health visitor if they are worried about their baby’s health. Screening does not identify all faulty genes that can cause CF and there remains a small chance that the baby could have the condition.

When a baby is identified as a carrier of the CF gene, it is recommended that parents consider finding out if they are carriers. This is because, when both parents are carriers, all future children have a 1 in 4 chance of developing CF. Parents should be advised to discuss this with their GP who can make a referral for genetic counselling.

2.4 Screening protocol

The screening protocol for CF is available in the CF laboratory guide.

The protocol is based on an initial analysis of immunoreactive trypsinogen (IRT) levels in the blood spot sample to identify babies at higher risk of CF. If the IRT levels indicates a higher risk, DNA testing is carried out on the same sample to look for CF causing genes.

2.5 Second blood spot sample

For some babies, their initial screening test is inconclusive. A repeat blood spot sample is needed to complete the test. This sample should be collected on day 21 (and no later than day 24 in exceptional circumstances) (day of birth is day 0). If the baby is already older than this, the second blood spot sample should be collected as soon as possible or as advised by the laboratory.

Sample takers should explain the reason for the second blood spot sample. Information sheets are available for both healthcare professionals and parents.

2.6 Clinical referral

Managing positive results from CF screening supports referral of all CF screen positive babies to diagnostic and clinical care in line with national guidelines and standards.

The document includes guidelines for managing babies with screening results of:

  • CF suspected
  • probable carrier, low likelihood of CF
  • CF not suspected following a second blood spot sample

The document also contains guidelines on communicating these results to parents.

Guidance is also given on evaluating and managing babies with an unclear diagnosis after CF newborn screening known as ‘CF screen positive, inconclusive diagnosis’ (CFSPID) cases. These are babies with:

  • a normal sweat chloride result and 2 faulty copies of the CFTR gene, at least one of which has unclear clinical outcome; or
  • an intermediate sweat chloride result and one or no faulty copies of the CFTR gene

CF clinical teams follow European CF Society (ECFS) guidance when managing these babies.

2.7 Information leaflets

These leaflets are available online:

2.8 Template letters

Template letters are available for the screening laboratory to notify:

2.9 Follow up forms

Follow up forms are available for:

  • CF suspected results: the CF clinical team must complete and return this form to the screening laboratory within 24 hours of the baby’s diagnostic assessment appointment
  • CF carrier results: the healthcare professional that has communicated the results to parents must complete and return this form to the screening laboratory within 24 hours of informing the parents

2.10 Notification of CF diagnosis not identified through screening

The CF centre and newborn screening laboratory must use this form to inform the screening programme about CF diagnoses that are not detected by screening (also known as ‘affected not detected’ cases).

2.11 More information

Information on CF is available on NHS.UK and from the Cystic Fibrosis Trust.

3. Congenital hypothyroidism

About 1 in 2,000 babies born in the UK has congenital hypothyroidism (CHT). CHT is present at birth. It is a condition where babies do not produce enough of the thyroid hormone thyroxine. Thyroxine is essential for normal growth and development and is regulated by thyroid stimulating hormone (TSH), produced by the pituitary gland.

CHT has several causes, including:

  • abnormal development with complete absence of the thyroid gland (‘agenesis’)
  • abnormal development of the thyroid gland, it has only partially formed or is in the wrong place (an ‘ectopic thyroid’)
  • a problem with thyroid hormone production by the thyroid gland even though it is in the normal position in the neck (‘dyshormonogenesis’)

These types of hypothyroidism are called ‘primary hypothyroidism’ because the problem is with the thyroid gland itself. Dyshormonogenesis is an inherited condition with around a 1 in 4 chance of other siblings being affected. The cause of most cases of thyroid agenesis and an ectopic thyroid gland are unknown.

There is also a condition called ‘secondary hypothyroidism’. This occurs when the pituitary gland produces inadequate TSH leading to reduced levels of thyroxine. This is not detected by the screening programme.

As well as being present at birth, hypothyroidism can be acquired at any time during childhood or adulthood. NBS screening in the UK only detects cases of primary hypothyroidism present from birth.

3.1 Symptoms

Babies with CHT do not normally have symptoms at birth. If untreated, babies do not grow properly and can develop learning disability. In general, patients with complete absence of the thyroid gland (agenesis) are the most severely affected, if untreated.

Some babies have ‘transient hypothyroidism’. They have hypothyroidism in early life but it resolves on its own later in childhood. Transient hypothyroidism may be caused by the transfer of maternal antibodies in pregnancy or rarely by exposure to iodine in antiseptics used after birth.

Preterm babies are at risk of having low thyroxine levels due to several factors, including immaturity of thyroid gland function, the effects of acute illness and/or the use of iodine containing compounds in imaging and at the time of surgery. It is unclear whether preterm babies are at increased risk of having permanent CHT when compared to full term babies.

3.2 Treatment

Early treatment of CHT with thyroxine is effective in preventing physical and learning disability. Thyroxine is given as a solution or in the form of crushed tablets taken by mouth.

3.3 Screening protocol

The screening protocol for CHT is available in the CHT laboratory guide.

The protocol is based on analysis of TSH levels in the blood spot sample. Some babies have a ‘borderline’ result and need a repeat blood spot sample taken 7 to 10 days after the initial sample.

3.4 Second blood spot sample for preterm babies

The TSH based screening test may not detect CHT in preterm babies because they can show a delayed rise in TSH levels after birth.

Babies born at less than 32 completed weeks gestation (less than or equal to 31 weeks + 6 days) need a second blood spot sample taken after the day 5 sample for CHT screening. This repeat is taken at 28 days of age (day of birth is day 0) or on the day of discharge home from hospital, whichever is sooner.

3.5 Clinical referral

The ‘CHT Initial Clinical Referral Standards and Guidelines’ (available in the CHT laboratory guide) support referral of CHT screen positive babies to diagnostic and clinical care.

3.6 Information leaflets

These leaflets are available online:

3.7 Template letters

Template letters are available for the screening laboratory to notify:

3.8 More information

Information on CHT is available from the British Thyroid Foundation and the British Society for Paediatric Endocrinology and Diabetes.

4. Inherited metabolic diseases

Inherited metabolic diseases (IMDs) are rare but serious inherited conditions. Babies with these conditions may have problems processing amino acids (the building blocks of proteins) or breaking down fats quickly enough to produce energy.

IMDs are autosomal recessive conditions. This means that babies are only born with an IMD if they inherit 2 faulty copies of the gene involved, one from each parent.

Babies with IMDs cannot usually produce a particular enzyme needed for metabolism. Enzymes help to convert one type of molecule into another. Enzyme deficiency may cause a build-up of some molecules that are harmful.

Without treatment babies with some of these conditions can become suddenly and seriously ill, while others develop irreversible problems more slowly. The symptoms of the conditions are different; some may be life threatening or lead to severe developmental problems.

NBS screening in England tests for 6 IMDs. These are:

  • phenylketonuria (PKU)
  • medium-chain acyl-CoA dehydrogenase deficiency (MCADD)
  • maple syrup urine disease (MSUD)
  • isovaleric acidaemia (IVA)
  • glutaric aciduria type 1 (GA1)
  • homocystinuria (pyridoxine unresponsive) (HCU)

Scotland and Wales also screen for all 6 IMDs. Northern Ireland screens for PKU and MCADD and is planning to introduce screening for MSUD, IVA, GA1 and HCU.

4.1 PKU

About 1 in 10,000 babies born in the UK has PKU. Babies are born with PKU if they inherit 2 faulty copies of the phenylalanine hydroxylase (PAH) gene, one from each parent. The PAH gene provides instructions to make the PAH enzyme. Babies need this enzyme to break down an amino acid called phenylalanine found in food and milk, including breast milk and normal infant formula. In babies with PKU, reduced activity of the PAH enzyme causes a build-up of phenylalanine in the blood.

Symptoms

Although babies with PKU appear well in early life, it is important that they are treated. Without early treatment babies can develop brain damage, including serious learning difficulties.

Treatment

A special low protein diet can help treat babies with PKU. The aim of the diet is to reduce thebuild-up of phenylalanine which can cause learning difficulties and brain damage. However, babies need a small amount of phenylalanine to grow and develop. The specialist metabolic dietitian will teach parents how to measure and control their baby’s protein intake including breast milk. This dietetic management helps to reduce the build-up of harmful substances in the brain.

The specialist metabolic team will review the baby on a regular basis. This will include regular blood tests to monitor the level of phenylalanine in their blood.

Information leaflets

These leaflets are available online:

Screening and diagnostic protocols

Screening and diagnostic protocols for PKU are available in the IMD laboratory guide.

Template letters

Template letters are available for:

More information

Information on PKU is available on NHS.UK and from the National Society for Phenylketonuria (NSPKU).

4.2 MCADD

About 1 in 10,000 babies born in the UK has MCADD. Babies are born with MCADD if they inherit 2 faulty copies of the medium chain acyl-CoA dehydrogenase (MCADD) gene, one from each parent. The MCAD gene provides instructions to make the MCAD enzyme, which is needed for metabolism of medium chain fatty acids into energy.

In periods of fasting, stress or illness, the body’s demand for energy is higher and it uses its own fat reserves to produce energy. Babies with MCADD cannot do this due to deficiency in the MCAD enzyme.

Symptoms

When a baby becomes unwell, for example, when they have an infection or vomiting, they need to break down fats quickly for energy. Babies with MCADD are unable to do this and without treatment can present with the following symptoms:

  • appearing unusually tired and sluggish
  • vomitting
  • excessive sweating
  • rapid breathing
  • seizures (fits)

During a metabolic crisis the baby is treated with an emergency regimen. If MCADD is not treated, babies with MCADD can deteriorate, have fits and slip into a coma which can be life threatening.

Treatment

Babies with MCADD do not usually need any special medications. Day to day management is to avoid prolonged periods without eating.

Babies with MCADD should feed frequently and it is fine for them to be breast or bottle fed. They should eat a normal healthy diet and:

  • take frequent special high energy drinks when they are unwell, this includes common illnesses such as fever, diarrhoea or vomiting (see section on emergency regimen for more information)
  • avoid long periods without feeds during the newborn period and infancy even when well – the length of time a baby/child can go without eating is known as the maximum ‘safe fasting time’ and it varies depending on age

The specialist metabolic team will review the baby on a regular basis.

Information leaflets

These leaflets are available online:

Screening and diagnostic protocols

Screening and diagnostic protocols for MCADD are available in the IMD laboratory guide.

Template letters

Template letters are available for:

More information

Information on MCADD is available on NHS.UK and from BIMDG and Metabolic Support UK (formerly known as Climb).

4.3 MSUD

About 1 in 150,000 babies born in the UK has MSUD. Babies are born with MSUD if they inherit 2 faulty copies of the branched chain alpha-keto acid dehydrogenase (BCKAD) gene, one from each parent. The BCKAD gene provides instructions to make the BCKAD enzyme. Babies need this enzyme to break down some of the amino acids found in food and milk, including breast milk and normal infant formula.

Normally, the branched chain amino acids (leucine, isoleucine and valine) are broken down into simpler molecules called keto acids before being converted to energy.

Babies without the BCKAD enzyme are unable to completely break down the keto acids. There is a build-up of amino acids and keto acids which are harmful to the brain.

Symptoms

Symptoms of MSUD usually appear within the first few days or weeks after birth. They include:

  • vomiting or difficulty feeding
  • abnormal movement of the arms and legs
  • lethargy
  • progressive neurological deterioration
  • sweet smelling urine and sweat
  • poor feeding or loss of appetite
  • weight loss

Increased concentration of the amino acids and keto acids raises the risk of a metabolic crisis. During a metabolic crisis the baby is treated with an emergency regimen.

If not treated, babies with MSUD can deteriorate, have fits and slip into a coma. Without early treatment, babies can develop brain damage, including learning difficulties. This is due to high levels of harmful substances in the body and can be life threatening.

Treatment

A special low protein diet and dietary supplements can help treat babies with MSUD. Dietetic management can reduce the risk of a metabolic crisis and learning difficulties. The aim of the diet is to reduce the build-up of leucine, valine, isoleucine and alloisoleucine. However, babies need a small amount of these amino acids to grow and develop. The specialist metabolic dietitian will teach parents how to measure and control their baby’s protein intake, including breast milk. The specialist metabolic team will review the baby on a regular basis.

Information leaflets

These leaflets are available online:

Screening and diagnostic protocols

Screening and diagnostic protocols for MSUD are available in the IMD laboratory guide.

Template letters

Template letters are available for:

More information

Information on MSUD is available on NHS.UK and from BIMDG and Metabolic Support UK (formerly known as Climb).

4.4 IVA

About 1 in 150,000 babies born in the UK has IVA. Babies are born with IVA if they inherit 2 faulty copies of the isovaleryl-CoA dehydrogenase (IVD) gene, one from each parent. The IVD gene provides instructions to make the IVD enzyme. Babies need this enzyme to fully break down an amino acid called leucine found in food and milk, including breast milk and normal infant formula.

Normally, leucine is broken down into a substance called isovaleric acid. Babies with IVA are unable to break down isovaleric acid. This leads to a harmful build-up of the acid in the blood and urine.

Symptoms

Symptoms sometimes appear within the first few days or weeks after birth and may include:

  • developing a distinctive odour of ‘sweaty feet’
  • poor feeding or loss of appetite
  • weight loss

Increased concentration of isovaleric acid raises the risk of a metabolic crisis. During a metabolic crisis the baby is treated with an emergency regimen.

The symptoms of IVA vary between babies. Some babies are initially well but then develop vomiting and lethargy, progressing to coma (these symptoms could appear at a later age, usually triggered by an infection). Other babies present with chronic symptoms, such as failure to thrive and/or developmental delay, usually within the first year.

If not treated, babies with IVA can deteriorate, have fits and slip into a coma. Without early treatment, babies can develop brain damage, including learning difficulties. This is due to high levels of harmful substances in the body and can be life threatening.

932C>T variant IVA

There is another version of IVA, referred to as‘932C>T’ variant (a change in the IVD gene) which screening may identify. This is a mild form of IVA with a much lower risk of problems. When a baby with the 932C>T variant is well, no special treatment is needed. No special diet or medication is required, but a dietitian will monitor the baby’s feed intake.

Treatment

A special low protein diet and medication can help treat babies with IVA. Dietetic management can reduce the risk of a metabolic crisis and learning difficulties. The specialist metabolic dietitian will teach parents how to measure and control their baby’s protein intake, including breast milk. In addition, medication is given to help clear some of the body’s harmful substances. The specialist metabolic team will review the baby on a regular basis.

Information leaflets

These leaflets are available online:

Screening and diagnostic protocols

Screening and diagnostic protocols for IVA are available in the IMD laboratory guide.

Template letters

Template letters are available for:

More information

Information on IVA is available on NHS.UK and from BIMDG and Metabolic Support UK (formerly known as Climb).

4.5 GA1

About 1 in 300,000 babies born in the UK has GA1. Babies are born with GA1 if they inherit 2 faulty copies of the glutaryl-CoA dehydrogenase (GCDH) gene, one from each parent. The GCDH gene provides instructions to make the GCDH enzyme. Babies need this enzyme to break down glutaric acid derived from amino acids (lysine, hydroxyl-lysine and tryptophan) found in food and milk, including breast milk and normal infant formulas. Without this enzyme harmful levels of some substances accumulate in the blood and can make the child unwell.

Symptoms

Symptoms of GA1 usually don’t appear until a few months after birth. However, some babies are born with a larger than average head called macrocephaly.

Increased concentration of harmful substances including glutarate and 3-hydroxyglutarate raises the risk of a metabolic crisis. During a metabolic crisis the baby is treated with an emergency regimen.

If GA1 is not treated it can cause long term brain damage. This can affect muscle movement and the ability to sit, walk, talk or swallow. Some babies with GA1 are at risk of subdural haemorrhage. This is a serious condition where blood collects between the skull and the surface of the brain. In rare cases babies can also develop retinal haemorrhage (abnormal bleeding around the back of the eyes).

Treatment

A special low protein diet and dietary supplements can help treat babies with GA1. Dietetic management can reduce the risk of a metabolic crisis and brain damage. The aim of the diet is to reduce the build-up of harmful substances, which can cause metabolic crisis and brain damage. However, babies need a small amount of these amino acids to grow and develop. The specialist metabolic dietitian will teach parents how to measure and control their baby’s protein intake, including breast milk. In addition, L-Carnitine (medication) is given to help clear some of the body’s harmful substances. The specialist metabolic team will review the baby on a regular basis.

Information leaflets

These leaflets are available online:

Screening and diagnostic protocols

Screening and diagnostic protocols for GA1 are available in the IMD laboratory guide.

Template letters

Template letters are available for:

More information

Information on GA1 is available on NHS.UK and from BIMDG and Metabolic Support UK (formerly known as Climb).

4.6 HCU pyridoxine unresponsive

About 1 in 300,000 babies born in the UK has HCU. There are 2 types of HCU, pyridoxine responsive HCU and pyridoxine unresponsive HCU. Pyridoxine is also known as vitamin B6.

NBS screening only identifies the pyridoxine unresponsive form (about 50% of total HCU cases). Pyridoxine responsive HCU is generally identified later in life.

Babies are born with HCU if they inherit 2 faulty copies of the cystathionine β-synthase (CBS) gene, one from each parent. The CBS gene provides instructions to make the CBS enzyme.

The CBS enzyme converts homocysteine into cystathionine. Homocysteine is made from the amino acid methionine, which is found in food and milk, including breast milk and normal infant formula. Babies with HCU lack the CBS enzyme, resulting in the build-up of both homocysteine and methionine.

Symptoms

Symptoms of HCU usually do not appear until a few months or years after birth. Some babies can develop problems with their eyes, including severe short sightedness and dislocation of the lens which may cause blurred vision. Without early treatment, babies can develop brain damage, including learning difficulties. Babies might also develop bone and joint problems, and blood clots or strokes.

Treatment

In a few babies with HCU, the level of homocysteine can be controlled by giving pyridoxine (vitamin B6).

If treatment with pyridoxine doesn’t work, a special low protein diet and medication can help treat babies with HCU. The aim of the diet is to reduce intake of methionine and the build-up of homocysteine which can cause learning difficulties and brain damage. The specialist metabolic dietitian will teach parents how to measure and control their baby’s protein intake, including breast milk. This dietetic management helps to reduce the build-up of harmful substances in the brain.

The specialist metabolic team will review the baby on a regular basis. This will include regular blood tests to monitor the level of homocysteine in their blood.

Information leaflets

These leaflets are available online:

Screening and diagnostic protocols

Screening and diagnostic protocols for HCU are available in the IMD laboratory guide.

Template letters

Template letters are available for:

More information

Information on HCU is available on NHS.UK and from BIMDG and Metabolic Support UK (formerly known as Climb).

4.7 Metabolic crisis

A metabolic crisis is a period of acute illness when the effects of the IMD make the baby seriously ill. It can occur before treatment starts or be triggered by infections and other illnesses. Symptoms include:

  • poor feeding
  • sleepiness
  • floppiness
  • abnormal movements
  • vomiting
  • breathing difficulties and fast breathing
  • coldness

4.8 Emergency regimen

The emergency regimen is a glucose polymer (a special high sugar like drink). It is given to babies with MCADD, MSUD, IVA and GA1 when they become ill or are not feeding well. They are available on prescription from the baby’s GP.

If the baby is too ill to drink normally, the emergency regimen can by given by a nasogastric feeding tube (tube that goes down the nose and into the stomach). This makes sure the baby receives enough regimen when they do not take enough by mouth.

The specialist metabolic team will arrange for the baby to be seen regularly by a metabolic dietitian. The metabolic dietitian will provide detailed instructions on how to give the emergency regimen and use the nasogastric feeding tube safely.

For MCADD the emergency regimen is given to provide the body with plenty of energy and to help prevent the breakdown of body fats.

For MSUD the emergency regimen involves:

  • stopping milk and food that contain protein
  • giving a special amino acid formula with isoleucine and valine supplements to help control leucine levels in the blood
  • continuing other medications while the emergency regimen is being given

For IVA the emergency regimen involves:

  • stopping milk and food that contain protein
  • continuing other medications while the emergency regimen is being given

For GA1 the emergency regimen involves:

  • stopping milk and food that contain protein
  • giving lysine free amino acid formula
  • continuing other medications while the emergency regimen is being given

If a baby continues to deteriorate despite having the emergency regimen, the baby must be taken to an accident and emergency department.

4.9 Notification of IMD diagnosis not identified through screening

Screening laboratories and metabolic teams should complete this form to inform the screening programme about IMD diagnoses that are not detected by screening (sometimes known as ‘affected not detected’ cases).