Allele specific oligonucleotide (ASO) hybridization and dot-blot analysis

This representation of ASO hybridization with dot blot analysis shows how this technique can be used to distinguish between an individual who is homozygous for a normal gene from individuals homozygous or heterozygous for a mutation in this gene. Patient DNA is red, and probes are green. In this case a normal gene is detected by a probe with the normal sequence, and a mutant gene is detected by a probe with a mutant sequence. The point mutation is denoted by an "X".
Box 1: the normal probe is hybridized to spots of DNA "dotted" from a normal individual, an individual homozygous for the mutation, and an individual heterozygous for the mutation. The probe gives a signal for the normal and heterozygous individuals, but not the homozygous individual (who lacks the normal gene).
Box 2: the mutant probe is hybridized to spots of DNA "dotted" from a normal individual, an individual homozygous for the mutation, and an individual heterozygous for the mutation. The probe gives a signal for the homozygous and heterozygous individuals but not the normal individual (who lacks the mutant gene).