10 February 2015
Preconception and prenatal carrier screening form a part of routine care in the US, identifying couples in whom there is a risk of children being affected by a genetic disorder.
Traditionally this approach is based on identifying risk factors based on family history or ethnicity and suggesting specific screening tests on this basis; however
modern genome sequencing technologies are providing scope for significant expansion of carrier screening to include a ‘universal’ type test for many genetic disorders simultaneously. In the light of this new potential, leading US groups have issued a joint policy statement on the issue published in the journal Obstetrics and Gynaecology.
Expanded Carrier Screening in Reproductive Medicine - Points to Consider is released by the American College of Medical Genetics and Genomics (ACMG) in partnership with the American College of Obstetricians and Gynecologists, the National Society of Genetic Counselors, the Society for Maternal-Fetal Medicine and the Perinatal Quality Foundation.
The statement is intended to inform and guide healthcare providers offering or considering expanded carrier screening services and set out a minimum standard for screening. It emphasises that information does not replace current screening guidelines from relevant organisations, whilst noting that ‘further direction is likely’ in the future.
Statement co-author and ACMG Vice-President for Clinical Genetics Anthony R. Gregg commented: "this document does not advocate for or against the universal implementation of expanded carrier screening. There is a paucity of scientifically sound information to guide professional organizations in taking a firm stance".
The statement sets out to underline the potential advantages and disadvantages of a much wider and complex analysis for patients and clinicians. In particular, whilst traditional approaches have focused on serious disorders with a fetal, newborn or childhood onset, expanded panels typically include a much wider variety of conditions in terms of severity, consistency of presentation and age of onset. These often include conditions for which carrier screening is not recommended by professional bodies; examples cited include fragile X syndrome and factor V Leiden.
All of these issues make advising and managing patients much more difficult, and present greater challenges for patients themselves in understanding the screening and results. Proper consent is noted to require that patients understand issues such as that some conditions vary unpredictably in severity, and that a negative screening result does not necessarily mean that the corresponding condition will not arise.
The statement concludes that research will be needed to understand the impact of expanded carrier screening on stakeholders, including ‘a health care system that has a vested interest in reproductive outcomes’.