Cytogenetic notation

A karyotype is an ordered arrangement of chromosomes that is described by cytogenetic notation. A karyotype can be obtained from dividing cells (blood leukocytes, bone marrow, fibroblasts, amniocytes), but not from frozen or formalin-fixed cells. 

The proper cytogenetic notation for a female with Down s syndrome mosaicism is... 

A female with Turner s syndrome is denoted by which of the following cytogenetic notations ... 

The cytogenetic notation 46,XX,i(6q) refers to which fettered diagram above ... 

The answer is d. (Murray, pp 812—828. Scriver, pp 3—45. Sack, pp 57-84. Wilson, pp 123—148.) Mosaicism occurs when a chromosomal anomaly affects one of several precursor cells of an embryo or tissue. The two or more karyotypes that characterize the mosaic cells are separated by a slash in cytogenetic notation. The notation 47,XX,-I-2I denotes a cell line typical of a female with trisomy 21 (Down s syndrome), while 46,XX is the karyotype expected for a normal female. 

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