Isodicentric Y chromosome
46,X,idic(Y)(q11.2)
Also known as: idic(Y), isodicentric Yq11.2, dicentric Y
46,X,idic(Y)(q11.2) is an isodicentric Y, the most common structural abnormality of the Y chromosome: a mirror-image chromosome with two centromeres, formed by breakage and fusion within Yq11.2. Dicentrics are mitotically unstable, so idic(Y) is usually found in mosaic with a 45,X cell line, and the phenotype ranges from Turner syndrome to a male with infertility.
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What the notation means
46- total chromosome count (the normal human number)
X- sex chromosomes: a single X (monosomy X)
idic(Y)(q11.2)- an ISODICENTRIC chromosome idic(Y): chromosome Y breaks at Yq11.2 and is duplicated as a mirror image, giving one chromosome with two centromeres and two copies of the retained arm
Clinical notes
Turner syndrome (45,X and variants)
Loss of all or part of the second sex chromosome. 45,X (monosomy X) is classic; variants include an isochromosome i(Xq), a ring r(X), an idic(Y), and 45,X mosaicism (e.g. 45,X/46,XX). Short stature, ovarian dysgenesis/streak gonads, webbed neck, coarctation/bicuspid aortic valve, lymphedema.