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Microdissection – a precise method to disclose the parental origin of supernumerary marker chromosomes
Annales de Ge´ne´tique 43 (2000) 109–110 © 2000 E´ditions scientifiques et me´dicales Elsevier SAS. All rights reserved S 0 0 0 3 - 3 9 9 5 ( 0 0 ) 0 1 0 1 5 - 7/SCO
Case report
Microdissection – a precise method to disclose the parental origin of supernumerary marker chromosomes Ursula Friedricha*, Merete Buggeb, Mette Houmana, Karen Friis Henriksenb, Karen Brøndum-Nielsenc b
a Department of Microdissection, Institute of Human Genetics, University of Aarhus, 8000 Aarhus C, Denmark Department of Medical genetics, Institute of Medical Biochemistry and Genetics, University of Copenhagen, Denmark c Department of Medical Genetics, The John F. Kennedy Institute, Glostrup, Denmark
Received 29 February 2000; accepted 22 May 2000
isochromosome 18p / microdissection / parental origin
Microsatellite analysis in patients with supernumerary isochromosomes has been successfully employed to trace the parental origin of these chromosomes [1, 3]. However, the models proposed for formation of the tetrasomy of, for example, 18p are based on the deduced haplotypes for the normal chromosomes 18 and the isochromome 18p. Most cases of isochromosomes 18p originate from a ma-
Figure 1.
* Correspondence and reprints E-mail address: [email protected] (U. Friedrich).
ternal meioses II non-disjunction followed by a subsequent postzygotic misdivision [1, 3]. In a few cases alternative haplotypes could be determined from the pattern of the polymorphisms in the families. Therefore, identification of the i(18p) haplotypes by PCR analysis of DNA from microdissected i(18p) chromosomes would allow a precise analysis of the origin and mechanism of formation.
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U. Friedrich et al. / Ann. Ge´ne´t. 43 (2000) 109 – 110
Table I. DNA polymorphisms on the short arm of chromosome 18 in one family where the proband has de novo tetrasomy 18p. Locusa pter D18S59 D18S62 D18S53 D18S71 cen
Father 23 12 23 13
+i(18p)
i(18p)
1133 1122 1112 1444
00 22 11 44
Mother 13 12 13 24
crosatellite was not amplified using the DOP-PCR procedure. But since four different DNA markers are used, the probability that all four should have avoided amplification is very low. In our study only one of the four microsatellites tested did not give a result. Acknowledgements
a The loci on the short arm of chromosome 18 are ordered in columns corresponding to their relative order based on linkage analysis [2].
Supernumerary isochromosomes are easily detected on G-banded preparations. In five cells an isochromosome of the short arm of chromosome 18 was dissected. DNA was amplified by DOP-PCR [4]. Four different DNA polymorphisms were tested after PCR amplification of genomic DNA from the parents, the proband (+i(18p)) and the DOP amplified DNA from the proband’s isochromome 18p [1, 2]. The results are shown in figure 1 and table I, both demonstrating the maternal origin of isochromosome 18p. The advantage of the method employed is that only the polymorphisms of the isochromosome are compared to those of both parents from the respective chromosome arms. In that way problems relating to interpretation of dosage can be avoided. A disadvantage may be that a specific chromosomal region encompassing precisely the locus for a mi-
.
This study was supported by the Danish Research Council, grant no 9802737. Nanna Rendtorff is thanked for the layout of the figure. References [1] Bugge M., Blennow E., Friedric U., Petersen M.B., Pedeutour F., Tsezou A., Ørum A., Hermann S., Lyngbye T., Sarri C., Avramopoulos D., Kitsiou S., Lambert J.C., Guzda M., Tommerup N., Brøndum-Nielsen K., Tetrasomy 18p de novo: parental origin and different mechanisms of formation, Eur. J. Hum. Genet. 4 (1996) 160 – 167. [2] Bugge M., Collins A., Petersen M.B., Fisher J., Brandt C., Hertz J.M., Tranebjærg L., de Lozier-Blanchet C., Nicolaides P., Brøndum-Nielsen K., Morton N., Mikkelsen M., Non-disjunction of chromosome 18, Hum. Mol. Genet. 7 (1998) 661 – 669. [3] Eggermann T., Schubert R., Engels H., Apacik C., StengelRutkowski S., Haefliger C., Emiliani V., Ricagni C., Schwanitz G., Formation of supernumerary euchromatic short arm isochromosomes: parent and cell stage of origin in new cases and review of the literature, Ann. Ge´ne´t. 42 (1999) 75 – 80. [4] Friedrich U., Houman M., Sandgaard J., Rosgaard A., Sunde L., Microdissection of chromosome 2-between-arm intrachromosomal insertion, Eur. J. Hum. Genet. 8 (2000) 393 – 395.
Case report
Microdissection – a precise method to disclose the parental origin of supernumerary marker chromosomes Ursula Friedricha*, Merete Buggeb, Mette Houmana, Karen Friis Henriksenb, Karen Brøndum-Nielsenc b
a Department of Microdissection, Institute of Human Genetics, University of Aarhus, 8000 Aarhus C, Denmark Department of Medical genetics, Institute of Medical Biochemistry and Genetics, University of Copenhagen, Denmark c Department of Medical Genetics, The John F. Kennedy Institute, Glostrup, Denmark
Received 29 February 2000; accepted 22 May 2000
isochromosome 18p / microdissection / parental origin
Microsatellite analysis in patients with supernumerary isochromosomes has been successfully employed to trace the parental origin of these chromosomes [1, 3]. However, the models proposed for formation of the tetrasomy of, for example, 18p are based on the deduced haplotypes for the normal chromosomes 18 and the isochromome 18p. Most cases of isochromosomes 18p originate from a ma-
Figure 1.
* Correspondence and reprints E-mail address: [email protected] (U. Friedrich).
ternal meioses II non-disjunction followed by a subsequent postzygotic misdivision [1, 3]. In a few cases alternative haplotypes could be determined from the pattern of the polymorphisms in the families. Therefore, identification of the i(18p) haplotypes by PCR analysis of DNA from microdissected i(18p) chromosomes would allow a precise analysis of the origin and mechanism of formation.
110
U. Friedrich et al. / Ann. Ge´ne´t. 43 (2000) 109 – 110
Table I. DNA polymorphisms on the short arm of chromosome 18 in one family where the proband has de novo tetrasomy 18p. Locusa pter D18S59 D18S62 D18S53 D18S71 cen
Father 23 12 23 13
+i(18p)
i(18p)
1133 1122 1112 1444
00 22 11 44
Mother 13 12 13 24
crosatellite was not amplified using the DOP-PCR procedure. But since four different DNA markers are used, the probability that all four should have avoided amplification is very low. In our study only one of the four microsatellites tested did not give a result. Acknowledgements
a The loci on the short arm of chromosome 18 are ordered in columns corresponding to their relative order based on linkage analysis [2].
Supernumerary isochromosomes are easily detected on G-banded preparations. In five cells an isochromosome of the short arm of chromosome 18 was dissected. DNA was amplified by DOP-PCR [4]. Four different DNA polymorphisms were tested after PCR amplification of genomic DNA from the parents, the proband (+i(18p)) and the DOP amplified DNA from the proband’s isochromome 18p [1, 2]. The results are shown in figure 1 and table I, both demonstrating the maternal origin of isochromosome 18p. The advantage of the method employed is that only the polymorphisms of the isochromosome are compared to those of both parents from the respective chromosome arms. In that way problems relating to interpretation of dosage can be avoided. A disadvantage may be that a specific chromosomal region encompassing precisely the locus for a mi-
.
This study was supported by the Danish Research Council, grant no 9802737. Nanna Rendtorff is thanked for the layout of the figure. References [1] Bugge M., Blennow E., Friedric U., Petersen M.B., Pedeutour F., Tsezou A., Ørum A., Hermann S., Lyngbye T., Sarri C., Avramopoulos D., Kitsiou S., Lambert J.C., Guzda M., Tommerup N., Brøndum-Nielsen K., Tetrasomy 18p de novo: parental origin and different mechanisms of formation, Eur. J. Hum. Genet. 4 (1996) 160 – 167. [2] Bugge M., Collins A., Petersen M.B., Fisher J., Brandt C., Hertz J.M., Tranebjærg L., de Lozier-Blanchet C., Nicolaides P., Brøndum-Nielsen K., Morton N., Mikkelsen M., Non-disjunction of chromosome 18, Hum. Mol. Genet. 7 (1998) 661 – 669. [3] Eggermann T., Schubert R., Engels H., Apacik C., StengelRutkowski S., Haefliger C., Emiliani V., Ricagni C., Schwanitz G., Formation of supernumerary euchromatic short arm isochromosomes: parent and cell stage of origin in new cases and review of the literature, Ann. Ge´ne´t. 42 (1999) 75 – 80. [4] Friedrich U., Houman M., Sandgaard J., Rosgaard A., Sunde L., Microdissection of chromosome 2-between-arm intrachromosomal insertion, Eur. J. Hum. Genet. 8 (2000) 393 – 395.