The genotypic distribution among non-insulin-dependent diabetes mellitus (NIDDM) patients of a restriction fragment length polymorphism.

The genotypic distribution among patients of a marker allele, or restriction fragment length polymorphism (RFLP), can be used to determine the mode of inheritance of a disease-predisposing gene, if the association of the marker with the disease is sufficiently high. In the case of noninsulin-dependent diabetes mellitus (NIDDM), the RFLP in the 5'-flanking region of the human insulin gene does not allow discrimination between dominant and recessive modes of inheritance, or between any intermediate model. Also, it is demonstrated, in general, that the observation of a higher odds ratio for individuals with two copies of a marker allele than for individuals with at least one copy does not in itself imply a gene-dosage model.