MutaGEL® r-vitamin D3 contains a set of primers for amplification of the specific DNA sequence within the human vitamin D3 receptor gene VD3R. Amplificates of varying genotypes (start codon polymorphism) are characterized by subsequent specific restriction enzyme digestion. The rare variant (f, pathogenic) possesses a restriction site for the specific endonuclease, whereas the major variant (F, protective) does not. The amplified products obtained from the pathogenic DNA variant will therefore be cut into two fragments, whereas the protective DNA variant will not be cut. The identification of the existing genotype from the patient is done by subsequent analysis of the DNA fragments by gelelectrophoretic methods (Dr. Essrich, Biologisches Labor, Denzlingen).