[Genetic analysis of an infant with rare type of trisomy 21 syndrome].

OBJECTIVE

To investigate the genetic cause for an infant with mental retardation through molecular cytogenetic analysis.

METHODS

Conventional G-banding analysis of peripheral blood for the family was first conducted. Chromosomal microarray analysis (CMA) was performed to further ascertain the size and origin of the abnormal chromosome fragments of the patient.

RESULTS

We identified a Chinese infant who carries an unbalanced, maternally inherited karyotype 48, XY, +der(X) (Yqter→Yq11.221∷Xp22.31→Xqter), +21 in which karyotype and CMA analyses disclosed Xp22.31→Xqter duplication of 147.3 Mb and Yq11.221→Yq11.23 duplication of 12.7 Mb.

CONCLUSION

Accompany with cytogenetic analysis, CMA can accurately identify the origin and size of the abnormal chromosomes, contributing to the precisely genetic analysis.