Review
Carrier testing in children and adolescents

https://doi.org/10.1016/j.ejmg.2015.11.006Get rights and content

Abstract

Many international guidelines recommend that carrier testing in minors should be postponed either until the age of majority or until the child can be actively involved in the decision making process. Although a number of high school programs exist which provide carrier screening to adolescents in at-risk populations, recent guidelines published by the American Society of Human Genetics do not advocate this testing. Despite this, there are some circumstances in which carrier testing does occur in minors. This testing might be intentional, in which identification of carrier status is the goal of the test, or unintentional, where carrier status is identified as a by-product of testing. In this review we outline the situations in which carriers may be identified in childhood and the positions of professional guidelines that address carrier testing in children. We then review the arguments for and against carrier testing presented in the literature and compare this to the empirical evidence in this field.

Introduction

Genetic carrier testing for both autosomal recessive and X-linked conditions is performed primarily to provide information to individuals to enable future reproductive planning and informed choices. This is in contrast to testing to determine whether one is a ‘carrier’ of an autosomal dominant condition, where the purpose is to identify their risk of developing a genetic condition themselves. Results from this predictive or presymptomatic testing incur different psychological impacts that are beyond the scope of this review. There is a general acceptance that the best time to learn of one's carrier status is before, rather than during, pregnancy (British Medical Association Ethics Department, 2012). Although preconception carrier testing is strongly encouraged in adulthood, both with and without the presence of a family history of a genetic condition, population-based carrier screening is not widely available apart from in some specific communities, such as the Ashkenazi Jews, and certain regions, for instance Cyprus and Sardinia (Borry et al., 2011). Yet carrier testing in childhood is usually considered inappropriate (Borry et al., 2006). Although many international guidelines recommend testing should be postponed until age of majority, most commonly 18 years of age (Borry et al., 2006), consideration may be given to ‘mature minors’ who are less than 18 years but considered capable of making informed decisions about having genetic testing (Duncan and Delatycki, 2006).

Despite this, there are some circumstances in which carrier testing does occur in individuals who are less than 18 years of age. This testing might be intentional, in which carrier status is identified deliberately and is the goal of the test, or unintentional, where carrier status is identified as a by-product of testing that has been performed for other purposes. In this review we outline the situations in which carriers may be identified in childhood and the positions of professional guidelines that address carrier testing in children. We then review the arguments for and against carrier testing presented in the literature and compare this to the empirical evidence in this field.

Section snippets

Cascade carrier testing

There are two main situations when intentional carrier testing may occur. The first is in the context of a family history of a genetic condition, such as following the diagnosis of a child in the family. In this context, the parents and other adult family members are usually offered cascade testing to determine their carrier status. Although carrier testing is generally not recommended in any unaffected siblings of the affected child, technically this could also occur. The literature indicates

Unintentional or incidental carrier testing in children

Carrier status may be identified incidentally 
in three ways: through newborn screening, incidentally following diagnostic testing and during prenatal testing.

Guidelines and position statements

International guidelines typically do not support broad use of carrier testing or screening in children or adolescents, particularly for conditions where no medical benefit is derived from identifying carrier status (American Medical Association, 1995, ASHGBD, 1995, Committee on Bioethics et al., 2013, Human Genetic Society, 2008, Italian National Bioethics, 1999, Ross et al., 2013). A systematic review in 2006 identified 14 guidelines and position statements produced by 24 different groups

Ethical arguments for and against carrier testing in children

A number of arguments have been provided, both in professional guidelines and other opinion papers, against performing carrier testing in children. Often these arguments focus on the idea that performing carrier testing in childhood is not in the child's best interests.

Conclusions

Despite the cautious stance presented by the majority of the international guidelines that address carrier testing in children, a systematic review of the literature in 2010 identified that overall there is less evidence of psychosocial harm from carrier testing than predicted (Wade et al., 2010). However, the studies that have been conducted are small and limited in the contexts and variety of conditions for which testing has taken place. Further research is required, both for intentional and

Acknowledgements

Danya Vears would like to thank the Research Fund Flanders (Belgium), the Ministère de l’Économie, de l’Innovation et des Exportations du Québec, PSR-SIIRI-850 (Canada) and the Brocher Foundation, Geneva, Switzerland for their support.

References (95)

  • American Medical Association

    Testing Children for Genetic Status

    (1995)
  • American Society of Human Genetics Board of Directors, & American College of Medical Genetics Board of Directors

    Points to consider: ethical, legal, and psychosocial implications of genetic testing in children and adolescents

    Am. J. Hum. Genet.

    (1995)
  • B.J. Bain

    Neonatal/newborn haemoglobinopathy screening in Europe and Africa

    J. Clin. Pathol.

    (2009)
  • I. Balfour-Lynn et al.

    Testing carrier status in siblings of patients with cystic-fibrosis

    Arch. Dis. Child.

    (1995)
  • K. Barlow-Stewart et al.

    A genetic screening programme for Tay-Sachs disease and cystic fibrosis for Australian Jewish high school students

    J. Med. Genet.

    (2003)
  • C. Barnes

    Testing children for balanced chromosomal translocations: parental views and experiences

  • P. Borry et al.

    Genetic testing in asymptomatic minors background considerations towards ESHG Recommendations

    Eur. J. Hum. Genet.

    (2009)
  • P. Borry et al.

    Carrier testing in minors: a systematic review of guidelines and position papers

    Eur. J. Hum. Genet.

    (2006)
  • P. Borry et al.

    Attitudes regarding carrier testing in incompetent children: a survey of European clinical geneticists

    Eur. J. Hum. Genet.

    (2007)
  • P. Borry et al.

    Preconceptional genetic carrier testing and the commercial offer directly-to-consumers

    Hum. Reprod.

    (2011)
  • M.J. Bouva et al.

    Implementing neonatal screening for haemoglobinopathies in the Netherlands

    J. Med. Screen.

    (2010)
  • British Medical Association

    Testing of Adults and Children with a Family History of Genetic Disorder

    (1998)
  • British Medical Association Ethics Department

    Medical Ethics Today: the BMAs Handbook of Ethics and Law

    (2012)
  • L. Cavanagh et al.

    Long-term evaluation of genetic counseling following false-positive newborn screen for cystic fibrosis

    J. Genet. Couns.

    (2010)
  • A. Chapple et al.

    Predictive and carrier testing of children: professional dilammas for clinical geneticists

  • G.M. Christenhusz et al.

    The communication of secondary variants: interviews with parents whose children have undergone array-CGH testing

    Clin. Genet.

    (2014)
  • D.J. Ciske et al.

    Genetic counseling and neonatal screening for cystic fibrosis: an assessment of the communication process

    Pediatrics

    (2001)
  • A. Clarke

    The genetic testing of children

    J. Med. Genet.

    (1994)
  • A.J. Clarke et al.

    The genetic testing of children: a clinical perspective

  • C.L. Clow et al.

    Knowledge about and attitudes toward genetic screening among high-school-students – tay-sachs experience

    Pediatrics

    (1977)
  • Committee for Public Relations and Ethical Issues of the German Society of Human Genetics

    Statement on Genetic Diagnosis in Children and Adolescents

    (1995)
  • Committee on Bioethics et al.

    Ethical and policy issues in genetic testing and screening of children

    Pediatrics

    (2013)
  • S. Dalby

    GIG response to the UK clinical genetics society report “the genetic testing of children”

    J. Med. Genet.

    (1995)
  • D.S. Davis

    Genetic dilemmas and the child's right to an open future

    Rutgers Law J.

    (1997)
  • L. Denayer et al.

    The CF carrier status is not associated with a diminished self-concept or increased anxiety: results of psychometric testing after at least 1 year

    Clin. Genet.

    (1996)
  • D.S. Diekema

    Parental refusals of medical treatment: the harm principle as threshold for state intervention

    Theor. Med. Bioeth.

    (2004)
  • R.E. Duncan et al.

    Predictive genetic testing in young people for adult-onset conditions: where is the empirical evidence?

    Clin. Genet.

    (2006)
  • N.F. Dunn et al.

    Carrier testing in haemophilia A and B: adult carriers' and their partners' experiences and their views on the testing of young females

    Haemophilia

    (2008)
  • S.J. Durfy et al.

    Attitudes of high school students toward carrier screening and prenatal diagnosis of cystic fibrosis

    J. Genet. Couns.

    (1994)
  • G. Evers-Kiebooms et al.

    A stigmatizing effect of the carrier status for cystic fibrosis

    Clin. Genet.

    (1994)
  • J. Fanos et al.

    Never again joy without sorrow: the effect on parents of a child with Ataxia-Telangiectasia

    Am. J. Med. Genet.

    (1999)
  • J.H. Fanos et al.

    A mark on the arm: myths of carrier status in sibs of individuals with ataxia-telangiectasia

    Am. J. Med. Genet.

    (1999)
  • J. Feinberg

    The child's right to an open future

  • A. Fryer

    Inappropriate genetic testing of children

    Arch. Dis. Child.

    (2000)
  • A.A. Gason et al.

    Evaluation of a Tay-Sachs Disease screening program

    Clin. Genet.

    (2003)
  • P.C. Giordano et al.

    Genetic epidemiology and preventive healthcare in multiethnic societies: the hemoglobinopathies

    Int. J. Environ. Res. Public Health

    (2014)
  • R.Z. Hayeems et al.

    A systematic review of the effects of disclosing carrier results generated through newborn screening

    J. Genet. Couns.

    (2008)
  • View full text