Complex sentence: For a description of human karyotype see In 1--2% of the observed Down syndromes, some of the cells in the body are normal and other cells have trisomy 21, this is called mosaic Down syndrome (46,XX/47,XX, +21).
Split into simpler sentences: For a description of human karyotype see In 1--2% of the observed Down syndromes, some of the cells in the body are normal and other cells have trisomy 21. This is called mosaic Down syndrome (46,XX/47,XX, +21).