cytogenetic syndromes: those conditions of development marked by various physical and behavioral symptoms that stem from a deficiency, excess, or other gross defect in the number, size, or shape of the chromosomes in each of the body's cells. For example, in most girls with Turner's syndrome, one sex chromosome is missing (45,X); in most boys with Klinefelter's syndrome, the male's one X chromosome is duplicated (47,XXY); and in most boys with the supernumerary-Y syndrome, the male's Y chromosome is duplicated (47,XYY).
Dictionary of Sexology Project: Main Index