Exome and Genome Sequencing
Introduction Current standards for prenatal genetic screening and testing are highly focused on detection of aneuploidies that are compatible with live birth, including trisomy 21, which affects 1:600 newborns overall…
PEDIATRICS
Genetic Evaluation of Fetal Sonographic Abnormalities
Introduction Structural malformations, many of which can be diagnosed antenatally, are present in approximately 2%–3% of live births. Fetuses with structural malformations are at increased risk for an underlying genetic…
Ultrasound Markers for Aneuploidy in the Second Trimester
Introduction Soft ultrasound markers were initially described as a screening method for trisomy 21 to improve the detection rate over that based on age-related risk alone. Soft markers are not…
Cell-Free DNA Screening
Overview Cell-free DNA (cfDNA) screening has been rapidly introduced into prenatal care since it became clinically available in 2011. cfDNA screening can detect more than 99% of cases of trisomy…
Serum and Ultrasound Based Screening Tests for Aneuploidy
What Is the History of Serum Screening? Prenatal screening for aneuploidy has evolved dramatically over a short period of time. The purpose of prenatal screening for aneuploidy is to identify…
Molecular Genetics
Introduction In 2003, the sequencing of the human genome propelled the field of genetics in two important directions. Firstly, the concept of “genomics” emerged, which includes both the DNA sequence…
Carrier Screening for Genetic Conditions
Introduction Prenatal genetic carrier screening has evolved over a period of about 25 years. Advances in technology and health policy have ushered this evolution. With these changes, new terminology has…
Principles of Genetic Counseling
Overview Genetic counseling is a process of evaluating family history and medical information to advise patients of the risk of a genetic condition. This can have both a diagnostic and…
Cytogenetics: Part 2, Structural Chromosome Rearrangements and Reproductive Impact
What Are Structural Chromosome Rearrangements and How Frequently Are They Seen in the General Population? As part of cytogenetic testing, the structure of each chromosome is assessed for (1) evidence…
Cytogenetics: Part 1, General Concepts and Aneuploid Conditions
What Is Cytogenetics? Cytogenetics is the study of chromosomes and the clinical application of chromosome analysis for diagnostic purposes. This chapter will deal with traditional cytogenetics, which involves examination of…
