What is the role of cytogenetic studies in the workup of Down syndrome?

Updated: Apr 30, 2018
  • Author: Gratias Tom Mundakel, MBBS, DCH; Chief Editor: Maria Descartes, MD  more...
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Answer

The clinical diagnosis of trisomy 21 should be confirmed with cytogenetic studies. Karyotyping is essential to determine the risk of recurrence. In translocation Down syndrome, karyotyping of the parents and other relatives is required for proper genetic counseling (see the images below).

G-banded karyotype showing trisomy 21 (47,XY,+21). G-banded karyotype showing trisomy 21 (47,XY,+21).
G-banded karyotype showing trisomy 21 of isochromo G-banded karyotype showing trisomy 21 of isochromosome arm 21q type [46,XY,i(21)(q10)].

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