Cytogenetic studies were performed on 150 cases of Down's syndrome (DS)
in Iran. The standard trisomy 21 was found in 132 (88 % ) and translocation-trisomy
21 (+21) in 18 (12%) patients, i.e., t(21,21) in 1(0.63%) and mosaicism in
17(11.33%) cases.
The comparison of the frequencies for mosaicism between different
populations such as Denmark, Hungary, Egypt, Iraq, India, Australia and Iran
...