Non-phenotypic detection of osteopetrotic (op/op) mutation by using PCR-SSCP analysis

Mice homozygous for recessive mutation osteopetrosis (op/op) on chromosome 3 provide a unique model to study the mechanism of haematopoiesis in conjunction with bone formation. Based on the DNA sequence data recently reported, we established a PCR-SSCP (polymerase chain reaction--single strand conformation polymorphism) assay which identifies an amplified fragment having an insertional point mutation present in macrophage colony-stimulating factor (M-CSF) gene of op/op mice. With this assay, three genotypes, op/op, +/op, and +/+ can be distinguished. Although heterozygous (+/op) and normal (+/+) mice could not be discriminated phenotypically, we could generate op/op mutant mice starting from a single heterozygous (+/op) mouse using only the PCR-SSCP aided screening method. This assay will permit introduction of the op mutant into any strain to generate a new animal model to study the cytokine network and haematopoiesis.