Human karyotypes for teaching: (47, +18, Trisomy 18)

These karyotypes are abnormal. There is a complete set of chromosomes plus an extra copy of chromosome 18. ZWK99035 is from a male, ZWK99036 is from a female. These individuals may survive to birth, although with multiple severe mental and physical retardations. This condition is also known as Edward's syndrome.

Each karyotype is available in one of three forms:

  • The original unmodified smear. These may have extra material, and often have some chromosomes crossed, which makes them less useful for a class exercise in which students cut apart and arrange the individual chromosomes. Some of these files are TIFF files, some are JPEGs.
  • A copy of the original, with extraneous materials removed, crossed chromosomes separated, and all chromosomes separated slightly to faciliate cutting apart of the chromosomes in a printed copy. This form is intended for student use in an introductory biology class. These are all JPEG files.
  • A "key", with the chromosomes arranged in standard order. These are all JPEG files.

To transfer the image to your computer, click on the appropriate name below.

ZooWeb Number

Original image

Modified image










These karyotypes are from the Wisconsin State Laboratory of Hygiene. They are intended for use in teaching to help students study human chromosomes. Copyright for these images remains with the State Laboratory of Hygiene, apply to them for permission for any other use than non-profit teaching.

For technical information on the methodology by which these smears were created click here.


Do you have suggestions or corrections for this page? Please email Larry Phelps (

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