Complex mosaicism associated with trisomy 9.

Fetal karyotypes can be routinely obtained by chorionic villus biopsy, amniocentesis, or fetal blood sampling. Interpretation of results and subsequent counselling can be complicated by pseudomosaicism or mosaicism confined to the placenta or other tissues. We illustrate this by reporting a case of an abnormal fetus with a total of three karyotypically different cell lines (46,XX; 47,XX, +9; and 47,XX, +del(9) (q11) in different tissues (placenta, lung, gonad, and skin).