[Cytogenetic study of Down syndrome cases in southern Hainan Province and report of a rare case of abnormal karyotype].

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.