ACMG Statements and Guidelines
These online statements and guidelines are definitive and may be cited using the digital object identifier (DOI). These recommendations are designed primarily as an educational resource for medical geneticists and other healthcare providers to help them provide quality medical genetics services; they should not be considered inclusive of all proper procedures and tests or exclusive of other procedures and tests that are reasonably directed to obtaining the same results. Please refer to the leading disclaimer in each document for more information.
- With recent advances in DNA sequencing technology, it is now possible to begin to appreciate the full scope of DNA variation that arises over the course of an individual’s lifetime.1,2 Our understanding of how the human genome changes over time and in response to external exposures is growing with the improved availability of next-generation sequencing (NGS) based testing, including exome/genome sequencing of large patient cohorts. Clinical laboratories employing NGS-based methodologies can detect many types of DNA sequence variation including those that are present at a reduced variant allele fraction (VAF) (i.e., less than the 50% expected for a heterozygous germline finding).
- Pathogenic variants in the CFTR gene are causative of classic cystic fibrosis (CF) as well as some nonclassic CF phenotypes. In 2001, CF became the first target of pan-ethnic universal carrier screening by molecular methods. The American College of Medical Genetics and Genomics (ACMG) recommended a core panel of 23 disease-causing variants as the minimal set to be included in pan-ethnic carrier screening of individuals with no family history of the disease, and these variants were usually assessed using targeted methods.
- In 1980, Eric Engel1 first proposed the concept of uniparental disomy (UPD), in which both homologous chromosomes are inherited from one parent, with no contribution (for that chromosome) from the other parent. In 1988, the first case of a Mendelian disorder associated with UPD was reported, in which a child with cystic fibrosis (MIM 219700) had inherited two copies of a pathogenic variant in CFTR (MIM 602421) from a heterozygous carrier mother, with no contribution from the biological father.2
- This document represents an update to the proposed approach of the American College of Medical Genetics and Genomics (ACMG) to categorize laboratory-developed tests (LDTs) for inherited conditions according to risk.1 Risk classification has historically been a determinant of whether, and to what extent, the US Food and Drug Administration (FDA) has overseen and regulated clinical tests. LDTs for constitutional variants continue to proliferate without a comprehensive federal regulatory framework in place.