Korean J Lab Med.  2010 Apr;30(2):195-200. 10.3343/kjlm.2010.30.2.195.

Down-Turner Syndrome (45,X/47,XY,+21): Case Report and Review

• Ryu SW
• Lee G
• Baik CS
• Shim SH
• Kim JT
• Lee JS
• Lee KA

• KMID: 1096808
• DOI: http://doi.org/10.3343/kjlm.2010.30.2.195

Abstract

We report the case of a 3-yr-old boy with Down-Turner mosaicism and review the previous reports of Down-Turner syndrome with documented karyotyping and clinical features. The patient showed clinical features of Down syndrome without significant stigma of Turner syndrome. Cytogenetic analysis of peripheral blood preparations by using G-banding revealed mosaicism with 2 cell lines (45,X[29]/47,XY,+21[4]). FISH analysis revealed that 87.5% of the cells had monosomy X karyotype and 12.5% of the cells had XY karyotype; trisomy 21 was only detected in the Y-positive cells. We suggest that additional cells should be analyzed and molecular genetic studies should be conducted to rule out double aneuploidy when karyotypes with sex chromosome aneuploidies and mosaicism are encountered, as in our case of Down syndrome mosaic with sex chromosome aneuploidy.

Keyword

Double aneuploidy; Down-Turner syndrome; Mosaicism

MeSH Terms

Aneuploidy
Child, Preschool
Chromosome Banding
Chromosomes, Human, Pair 21
Chromosomes, Human, X
Chromosomes, Human, Y
Down Syndrome/complications/*genetics
Humans
In Situ Hybridization, Fluorescence
Karyotyping
Male
*Mosaicism
Trisomy
Turner Syndrome/complications/*genetics

Figure

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  Fig. 1. The G-banded karyotype of the patient showing mosaic double aneuploidy with a loss of Y chromosome (A) and addition of chromosome 21 (B) (arrows); 45,X[29]/47,XY,+21[4].

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  Fig. 2. FISH analysis with centromeric X (DXZ1; spectrum green) and centromeric Y (DYZ3; spectrum red) probes showing one 46,XY metaphase and five X interphases with one green signal indicating monosomy X.

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  Fig. 3. FISH analysis with CEP Y probe specific for Y chromosome (DYZ1; spectrum green) and DNA LSI probe specific for chromosome 21 (D21S259, D21S341, and D21S342; spectrum red) revealed that only those cells with a Y chromosome (green signal) show trisomy 21 (triplicate red signals).

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