TY - CHAP M1 - Book, Section TI - Cytogenetics & Cytogenomics A1 - Pyeritz, Reed E. A2 - Papadakis, Maxine A. A2 - McPhee, Stephen J. A2 - Rabow, Michael W. A2 - McQuaid, Kenneth R. PY - 2023 T2 - Current Medical Diagnosis & Treatment 2023 AB - Cytogenetics is the study of chromosomes by light microscopy. The chromosomal constitution of a single cell or an entire individual is specified by a standardized notation. The total chromosome count is determined first, followed by the sex chromosome complement and then by any abnormalities. The autosomes are all designated by numbers from 1 to 22. A plus (+) or minus (–) sign indicates, respectively, a gain or loss of chromosomal material. For example, a normal male is 46,XY, whereas a girl with Down syndrome caused by trisomy 21 is 47,XX,+21; a boy with Down syndrome caused by translocation of chromosome 21 to chromosome 14 in a sperm or an egg is 46,XY,–14,+t(14;21). SN - PB - McGraw-Hill Education CY - New York, NY Y2 - 2024/03/28 UR - accessmedicine.mhmedical.com/content.aspx?aid=1193140270 ER -