Fig. 12. High-resolution banding karyotype performed on peripheral blood. This is written as 46 XX t(6;7)(q23.1; q11.23). This means that a break has occurred in the long or “q” arms of one chromosome 6 and one chromosome 7 (arrows). Chromosomal material from each chromosome was switched, that is, translocated to the other chromosome. Since genetic material is not lost, this would be a balanced reciprocal rearrangement and would not usually cause phenotypic effects. An individual who carries this balanced rearrangement would be at increased risk for having an offspring with an unbalanced karyotype which would result in a miscarriage, a stillbirth, or a child with birth defects. (Courtesy of Paul Fernhoff, MD, Emory University Genetics Laboratory)