[Clinical and cytogenetic analysis of 257 cases of Down's syndrome].
Astete C, Youlton R, Castillo S, +2 more·Revista chilena de pediatria
Among 257 patients with clinical diagnosis of Down's syndrome, 56.4% of male gender, in whom cytogenetic studies were performed, 14 (5.4%) had normal karyotypes and 243 (94.6%) had 21 trisomy. Of these last, 225 (92.6%) had free 21 trisomy, 10 (4.1%) showed mosaics, 8 (3.3%) had translocations. Average maternal age of…