Genetic analysis of C4 polymorphism by use of DNA amplification (PCR), allele-specific oligonucleotide probes and allele-specific restriction enzymes.

In vitro DNA amplification allows multiplication of selected gene segments thereby improving the sensitivity in DNA analysis. Different allelic variants in the amplified DNA may be disclosed either by subsequent hybridization with allele-specific oligonucleotides or by subsequent allele-specific digestion with selected restriction endonucleases, followed by separation in agarose gel electrophoresis. The genes that code for human complement component C4 are polymorphic. Presently we demonstrate that allelic differences in C4, involving one base pair only, can be efficiently identified in the amplified DNA by each of the two techniques. A combination of both techniques may also be employed. The DNA amplification procedure may give access to selected 'haploid' fragments for individual DNA studies.