Identifying carrier status for thalassaemia, sickle cell disease, cystic fibrosis, or Tay-Sachs disease in non-pregnant women and their partners

Review question

We looked for evidence to show whether identifying people who are carriers for thalassaemia, sickle cell disease, cystic fibrosis, or Tay-Sachs disease, before pregnancy leads to improving reproductive choice and pregnancy outcomes.

Background

Across the world, about five per cent of children are born with genetic disorders. These disorders can be passed down from parent to child. There are tests to identify the genetic risk of the most common genetic disorders (thalassaemia, sickle cell disease, cystic fibrosis, or Tay-Sachs disease) before pregnancy. In these disorders, called autosomal recessive conditions, the parents of affected children are 'carriers' of the condition, which means they do not usually have symptoms. All 'carrier' couples will have a 25 per cent chance of having an affected child. Risk assessment for these genetic disorders prior to pregnancy would benefit potential parents who may be carriers. This information would give the at-risk couple the opportunity to make fully informed decisions about family planning. However, genetic risk assessment before pregnancy may potentially have a negative psychological impact.

Search date

We last looked for evidence on 10 December 2014.

Study characteristics

We did not find any trials that we could include in this review.

Key results

Although no trials were identified in which volunteers would have equal chances of being in either group, there are several studies which are not so strictly designed which support current policy recommendations for genetic risk assessment prior to pregnancy in routine clinical practice. Any future trials need to consider legal, ethical and cultural barriers to implementation.

Authors' conclusions: 

As no randomised controlled trials of preconception genetic risk assessment for thalassaemia, sickle cell disease, cystic fibrosis, or Tay-Sachs disease were found for inclusion in this review, the research evidence for current policy recommendations is limited to non-randomised studies.

Information from well-designed, adequately powered, randomised trials is desirable in order to make more robust recommendations for practice. However, such trials must also consider the legal, ethical, and cultural barriers to implementation of preconception genetic risk assessment.

Read the full abstract...
Background: 

Globally, about five per cent of children are born with congenital or genetic disorders. The most common autosomal recessive conditions are thalassaemia, sickle cell disease, cystic fibrosis and Tay-Sachs disease, with higher carrier rates in specific patient populations. Identifying and counselling couples at genetic risk of the conditions before pregnancy enables them to make fully informed reproductive decisions, with some of these choices not being available if genetic counselling is only offered in an antenatal setting.

Objectives: 

To assess the effectiveness of systematic preconception genetic risk assessment to improve reproductive outcomes in women and their partners who are identified as carriers of thalassaemia, sickle cell disease, cystic fibrosis and Tay-Sachs disease in healthcare settings when compared to usual care.

Search strategy: 

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group's Trials Registers. In addition, we searched for all relevant trials from 1970 (or the date at which the database was first available if after 1970) to date using electronic databases (MEDLINE, Embase, CINAHL, PsycINFO), clinical trial databases (National Institutes of Health, Clinical Trials Search portal of the World Health Organization, metaRegister of controlled clinical trials), and hand searching of key journals and conference abstract books from 1998 to date (European Journal of Human Genetics, Genetics in Medicine, Journal of Community Genetics). We also searched the reference lists of relevant articles, reviews and guidelines and also contacted subject experts in the field to request any unpublished or other published trials.

Date of latest search of the registers: 25 June 2015.

Date of latest search of all other sources: 10 December 2014.

Selection criteria: 

Any randomised or quasi-randomised control trials (published or unpublished) comparing reproductive outcomes of systematic preconception genetic risk assessment for thalassaemia, sickle cell disease, cystic fibrosis and Tay-Sachs disease when compared to usual care.

Data collection and analysis: 

We identified 19 papers, describing 13 unique trials which were potentially eligible for inclusion in the review. However, after assessment, no randomised controlled trials of preconception genetic risk assessment for thalassaemia, sickle cell disease, cystic fibrosis and Tay-Sachs disease were found.

Main results: 

No randomised controlled trials of preconception genetic risk assessment for thalassaemia, sickle cell disease, cystic fibrosis and Tay-Sachs disease were found.

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