THE MYELIN BASIC-PROTEIN GENE IN MULTIPLE-SCLEROSIS - IDENTIFICATION OF DISCRETE ALLELES OF A 1.3 KB TETRANUCLEOTIDE REPEAT SEQUENCE

Myelin basic protein (MBP) is a potential autoantigen in multiple scle rosis (MS) and its gene therefore is an attractive candidate to confer genetic susceptibility to this disease. Linkage and association with certain alleles of a 1.2 kb tetranucleotide repeat region 5' to the MB P gene with MS have been reported in Finnish patients, and an associat ion has been reported from Denmark. However, these findings have not b een confirmed in subsequent analyses in other populations. A limitatio n of previous studies has been the low resolution of the typing proced ure. We have investigated the same polymorphism in thirty-four Swedish nuclear families with 2 or 3 MS patients, and in 149 unrelated Swedis h MS patients and 95 healthy controls using a fluorescence-based semi- automated technique which allowed the identification of discrete tetra repeat numbers. Neither parametric two-point linkage analysis nor a no nparametric affected pedigree members analysis showed any sign of link age. In addition, the distribution of alleles was similar in patients and controls. We conclude that the MBP gene does not influence suscept ibility to MS in Swedish patients.