(1992) Abdul Matlib and his family from Bangladesh who were reunited in Britain after DNA testing proved blood relation. He is looking at the DNA autoradiogram that proved his blood relationships. DNA consists of two sugar- phosphate backbones, arranged in a double helix, linked by nucleotide bases. There are 4 types of base; adenine (A), cytosine (C), guanine (G) and thymine (T). Sequences of these bases make up genes, which encode an organism's genetic information. The bands (black) on the autoradiograms show the sequence of bases in a sample of DNA. DNA Fingerprinting.