Objective: To investigate the distribution and characteristic of the karyotypes in Down syndrome (DS) patients in southern Hainan Province, China.
Methods: Cytogenetic analysis was carried out in 132 cases clinically suspected of DS.
Results: Eighty-six of the cases were diagnosed as DS with karyotype analysis. Among the DS patients in southern Hainan, 93.02% of the cases had typical trisomy 21, 3.49% had translocation, and 3.49% had mosaic karyotype. The percentage of DS babies born by younger mothers (<35 years) was greater than that of the babies born by elder mothers (91.86% vs 8.14%). In addition, a case of translocation between chromosomes 5 and 8 with regular trisomy 21 was identified, which represented the first case ever reported.
Conclusion: Typical trisomy 21 karyotype is more frequent in DS cases than translocation and mosaic karyotypes in southern Hainan Province, where the mother delivering a child with DS tends to be younger.