Clinical Guidelines and Standards · Guidelines by Issuing Body

Screening for autosomal recessive and X-linked conditions during pregnancy and preconception: a practice resource of the American College of Medical Genetics and Genomics (ACMG)

Gregg AR, Aarabi M, Klugman S, Leach NT, Bashford MT, Goldwaser T, Chen E, Sparks TN, Reddi HV, Rajkovic A, Dungan JS, ACMG Professional Practice and Guidelines Committee

Published October 2021 Genet Med
DOI 10.1038/s41436-021-01203-z PMID 34285390 PMC PMC8488021

RRM Academy Synopsis

ACMG recommends Tier 3 carrier screening before and during pregnancy

ACMG recommends offering Tier 3 carrier screening to patients who are pregnant or planning pregnancy, a 2021 consensus practice resource states. Tier 3 sets a carrier frequency threshold of at least 1/200 for autosomal recessive conditions. The Tier 3 list is made up of 97 autosomal recessive genes and 16 X-linked genes.

Key Findings

  • Tier 1 is cystic fibrosis and spinal muscular atrophy; Tier 2 severe or moderate conditions at carrier frequency of at least 1/100; Tier 3 at least 1/200; Tier 4 no lower limit.
  • The consensus group recommends 97 autosomal recessive genes for Tier 3 screening, and identified 16 genes for X-linked conditions.
  • Male partners of pregnant patients and those planning pregnancy may be offered Tier 3 autosomal recessive screening when it is done simultaneously with the female partner.
  • ACMG suggests reserving Tier 4 for known or possible consanguineous relationships (second cousins or closer) and for family or personal history that warrants it, and does not recommend routine Tier 4 panels.
  • Survey studies of more than 470,000 screened patients: in the two largest, a majority (~60%) of responding at-risk couples took some action, more often (62–77%) when results came before pregnancy.

Interpretation

The paper is a consensus practice resource from an ACMG committee. Its methods section describes a consensus group that developed and answered eight questions. The evidence for utility comes from a few survey studies. The paper defines utility as people receiving information and possibly changing reproductive decisions. The authors note that these studies may not reflect ethnically diverse populations. Carrier frequency thresholds refer to ethnic groups represented in the United States. Most autosomal recessive genes came from the gnomAD population database, and X-linked conditions from the OMIM database. Four authors direct molecular testing laboratories offering carrier screening, and a fifth reports a laboratory services role.

RRM Context

The paper's counseling guidance states that carrier screening ideally belongs in preconception care, and it allows testing of both partners. Restorative reproductive medicine likewise evaluates both partners before treatment. The resource addresses the chance of a genetic condition in a child. Fertility evaluation, such as ovulation and tubal health, is outside its scope.

Abstract

Carrier screening began 50 years ago with screening for conditions that have a high prevalence in defined racial/ethnic groups (e.g., Tay-Sachs disease in the Ashkenazi Jewish population; sickle cell disease in Black individuals). Cystic fibrosis was the first medical condition for which panethnic screening was recommended, followed by spinal muscular atrophy. Next-generation sequencing allows low cost and high throughput identification of sequence variants across many genes simultaneously. Since the phrase "expanded carrier screening" is nonspecific, there is a need to define carrier screening processes in a way that will allow equitable opportunity for patients to learn their reproductive risks using next-generation sequencing technology. An improved understanding of this risk allows patients to make informed reproductive decisions. Reproductive decision making is the established metric for clinical utility of population-based carrier screening. Furthermore, standardization of the screening approach will facilitate testing consistency. This practice resource reviews the current status of carrier screening, provides answers to some of the emerging questions, and recommends a consistent and equitable approach for offering carrier screening to all individuals during pregnancy or preconception.

Topics

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Related research

Clinical Guidelines and Standards › Guidelines by Issuing Body › United States Professional Societies · Genetics and Immunology › Reproductive Genetics › Carrier Screening
Anthony R Gregg, Mahmoud Aarabi, Susan Klugman, Natalia T Leach, Michael T Bashford, Tamar Goldwaser, Emily Chen, Teresa N Sparks, Honey V Reddi, Aleksandar Rajkovic, Jeffrey S Dungan
Tony Gregg, A Gregg, M Aarabi, Sue Klugman, S Klugman, N Leach, Mike Bashford, M Bashford, T Goldwaser, E Chen, T Sparks, H Reddi, A Rajkovic, Jeff Dungan, J Dungan
PMID 34285390 34285390 DOI 10.1038/s41436-021-01203-z 10.1038/s41436-021-01203-z Gregg et al. 2021, Gregg 2021