By the end of this session you will have attempted:

1. To prepare a normal karyotype from a metaphase to use as a standard for future comparisons. You are provided with a photo editor and photo files of normal metaphases. See Exercise 1 & 2 in the 'Methods' page.

2. To identify individual bands using a diagram (here called an idiogram), and see their gene content and the pathology associated with constitutional deletions/duplications of different regions of the karyotype. See Exercise 3 in the 'Methods' page.

3. To prepare and read a karyotype from clinical samples of acquired disorders (tumors), constitutional disorders and prenatal samples. Some pictures are available.

4. To interpret the result in the clinical context of the sample, making use of public databases. See Exercise 4 in the 'Acquired' page.

5. The principles and clinical applications of Fluorescence In Situ Hybridisation (FISH) on interphase and metaphase nuclei, and of related fluorescence technologies such as Colour Karyotyping, (for instance, Spectral Karyotyping or SKY) and Comparative Genomic Hybridisation (CGH). See Exercise 5 & 6 in the F.I.S.H. page.

To do these exercises, you will find your banded metaphases in the 'Tools' page. Instead of scissors and paste, here you will use a simple photoeditor to cut and paste the chromosomes from those metaphases. The procedure to use the photoeditor for this purpose is explained under the button 'Methods' (on the left). The address to download the photoeditor is given in the course's introductory page.

Clinical cytogenetics deals with three types of situation; constitutional disease, acquired disease (tumours) and prenatal diagnosis. To put your result in its context, there are some references and comments on each of these in the corresponding buttons on the top left of this page. Lastly, there is a separate button xontaining some technical notes on Fluorescence In Situ Hybridsation (F.I.S.H.)

Note on Karyotyping

Karyotyping consists in arraging the chromosomes from a metaphase plate in homologous pairs. The purpose of the pairing is to show up any possible differences in size, shape or banding between the homologous chromosomes. In principle, in normal individuals both homologues are nearly identical. Normally one homologue is paternal and the other maternal in origin. There are some known polymorphic bands/regions rich in constitutive heterochromatin where variations are not associated with any clinical effect (i.e. around the centromeres, particularly of Nos. 1, 3, 9, 16, and the distal region of Yq).

This first three exercise consist in training your eye to distinguish matching pairs in a metaphase plate. For these exercises, use 'standard' metaphase plates 1 to 3 from the 'Tools' page. You will learn to count and identify individual chromosomes and match them in pairs. If you compare the different metaphases provided, you will notice that in some the chromosomes are relatively longer and contain more bands. Remember that when looking at banded metaphases using these standard Black and White techniques you have three criteria to match the pairs; size, shape (i.e., position of the centromere) and banding pattern). You will also use a tool showing standard diagrams for the identification of each band, and displaying their gene contents.