TY - CHAP M1 - Book, Section TI - Laboratory Analysis of Copy Number and Single Nucleotide Variants A1 - Harel, Tamar A1 - Lupski, James R. A1 - Liu, Pengfei A2 - Kline, Mark W. PY - 2018 T2 - Rudolph's Pediatrics, 23e AB - Cytogenetics is a field of genetics involved with the study of chromosomes. Clinical cytogenetics aims to delineate the gross chromosomal abnormalities, both in number and structure, associated with certain malformation syndromes. Approximately 1% of live-born babies have a cytogenetic abnormality, making this field particularly relevant in the pediatric population and the clinical practice of pediatrics. Cytogenetics includes routine analysis of G (Giemsa)-banded chromosomes, fluorescence in situ hybridization (FISH), and whole-genome array comparative genomic hybridization (aCGH) and single nucleotide polymorphism (SNP) arrays. Whole-genome sequencing (WGS), which has been viewed traditionally as a molecular technique targeting single nucleotide variants (SNVs), is gradually being introduced into the cytogenetics field because of its potential to analyze copy number variants (CNVs) as well as structural variants (SVs). WGS can be implemented postnatally as well as prenatally, from fetal DNA in maternal blood. Whole-exome sequencing (WES) focuses on the coding sequences of all genes in the human genome (~1% of the human genome). It detects small changes in DNA including SNVs and indels (insertions and deletions <50–100 bp). WES has been particularly useful clinically for elucidating the etiologic molecular diagnosis in pediatric patients whose phenotype remained a diagnostic dilemma and for finding dual molecular diagnoses in patients with blended phenotypes. SN - PB - McGraw-Hill Education CY - New York, NY Y2 - 2024/03/29 UR - accesspediatrics.mhmedical.com/content.aspx?aid=1182930618 ER -