A repetitive DNA sequence 5' to the human myelin basic protein gene may be linked to MS in Danes.

The myelin basic protein (MBP) gene is a candidate locus for disease susceptibility in multiple sclerosis (MS). In the present study a part of the tetranucleotide (TGGA)n repeat polymorphism 5' to the MBP gene was examined in 90 Danish MS patients and 106 controls. Lymphocyte DNA was isolated and used in PCR assay. The PCR fragments produced were separated by agarose and acrylamide electrophoresis. Hereby we found three different bandpatterns i.e. a homozygote with a 450 bp fragment, a homozygote with a fragment 375 bp and a heterozygote with both bands present. The 450 bp fragment occurred significantly more often among MS than in the control group and the 375 bp fragment was underrepresented among MS than in the control group. The differences between incidence of the three band pattern in the MS and the control group were significant different at 1% level. Our study thus indicate that there is an association between MS and a length polymorphism of the 5' end to the MBP gene in Danish MS patients.