A New Molecular Genetic Diagnosis of the Btk Mice

A new method of polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis was developed for genetic typing of a point mutation of the Bruton’s tyrosine kinase (Btk) gene in CBA/N mice bearing an X-linked recessive immunodeficiency (xid). Since restriction site useful for RFLP analysis does not exist in the spontaneous mutant Btk locus, an artificial restriction site was introduced by PCR amplification with a modified primer. The five genotypes of the Btk locus (Btk/ Btk, Btk /Btk+ and Btk+/Btk+ females and Btk/Btk and Btk/Btk males) could be distinguished by three patterns clearly and easily. This PCR-RFLP analytic method will be useful as a tool in the production of congenic mice and mice with multiple immunodeficient genes.