Current UK NSC recommendations > Amino acid metabolism disorders

The UK NSC recommendation on Amino acid metabolism disorders screening in newborns (currently in consultation)


This recommendation is currently being reviewed as part of the UK NSC's regular review cycle of all policies.

The review process began in Jul 2016 and is estimated to be completed by Nov 2016.

» Download the expert review for Amino acid metabolism disorders (PDF document, 1.96MB)

The UK NSC welcomes comments and feedback on the expert review during the consultation period that lasts from 20/07/2016 until 04/11/2016. Please send comments to Adrian Byrtus by e-mail using this feedback form.

Please note that all consultation submissions will be published on this page when the review is complete. Full details can be found in the confidentiality and disclosure section at the bottom of this page.

Recommendation Systematic population screening programme not recommended

This is a consultation of screening for Tyrosinaemia Type 1 only.

The initial review of tyrosinaemia type 1 that was undertaken in March 2015 identified many outstanding uncertainties regarding the epidemiology, the test cut off and the long term outcomes from early treatment with Nitisinone. This evidence review has been commissioned due to the consultation responses received suggesting that studies published after the initial review’s literature search may contribute to the resolution of some of the uncertainties.


This policy covers the following rare inherited amino acid metabolism disorders:

  • Argininosuccinate lyase deficiency
  • Citrullinaemia
  • Tyrosinaemia type I

NB: the policy for Phenylketonuria and Homocystinuria screening are considered separately.


Find general information about population health screening.

Why is screening not recommended by UK NSC?

The UK NSC does not currently recommend screening for the amino acid metabolism disorders; Tyrosinaemia type 1, Citrullinaemia (CIT) and Argininosuccinate lyase (ASL) deficiency in newborn babies. This is because: -

  • Babies with CIT often develop symptoms before the results of the screening test would be available. Additionally, the test would falsely identify some healthy babies as having the condition.
  • The long term effects of ASL Deficiency, such as liver disease and brain damage, appear to be unaltered by early treatment.
  • The review, and public consultation, suggested that screening for tyrosinaemia type 1 may be possible. The UK NSC is undertaking further work to explore the issues raised in the consultation. This includes evaluating the accuracy of the test and effectiveness of the treatment.

More about Amino acid metabolism disorders

Amino acid metabolism disorders are a group of inherited conditions caused by a particular enzyme (a chemical found naturally in the body) being faulty or missing. This leads to problems breaking down certain amino acids. Amino acids are the building blocks of proteins and are metabolised in order to provide energy or to make other needed compounds.

This disorder leads to a build up of unwanted chemicals that can cause damage to vital parts of the body such as the liver.

» Read more about amino acid metabolism disorders at the Climb National Information Centre for Metabolic Diseases website


British Inherited Metabolic Disease Group
Children Living with Inherited Metabolic Diseases
Clinical Genetics Society
Faculty of Public Health
Genetic Alliance UK
Institute of Child Health
Rare Disease UK
Royal College of General Practitioners
Royal College of Midwives
Royal College of Paediatrics and Child Health
Save Babies Through Screening Foundation UK
UK Newborn Screening Laboratories Network

The stakeholder groups will be involved when the recommendation is next reviewed. If you think your organisation should be added, please contact us. More information for stakeholders can be found in appendix C of the UK NSC evidence review process.

Related documents

icon Ethical, Social and Legal Issues with Expanding the Newborn Blood Spot Programme (PDF document, 2.13MB, 21/11/14)

Confidentiality and disclosure

Information provided in response to this consultation, including personal information, may be subject to publication or release to other parties or to disclosure in accordance with the access to information regimes (these are primarily the Freedom of Information Act 2000, the Data Protection Act 1998, and the Environmental Information Regulations 2004). If you want information, including personal data that you provide to be treated as confidential, please be aware that, under the FOIA, there is a statutory Code of Practice with which public authorities must comply and which deals, amongst other things, with obligations of confidence.

In view of this it would be helpful if you could explain to us why you regard the information you have provided as confidential. If we receive a request for disclosure of the information we will take full account of your explanation, but we cannot give an assurance that confidentiality can be maintained in all circumstances. An automatic confidentiality disclaimer generated by your IT system will not, of itself, be regarded as binding on the UK National Screening Committee.

Any request for information to be treated in confidence will be taken into consideration in the publication of responses to the consultation. The UK National Screening Committee intends to publish all responses following the closure of the consultation period, however we will not publish responses from respondents who request that any of the information in their response, including personal data, should be handled in confidence. The UK National Screening Committee reserves the right not to publish or take into account any representations which are openly offensive or defamatory.

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