Linkage relationships of the apolipoprotein C1 gene and a cytochrome P450 gene (CYP2A) to myotonic dystrophy.

We have studied the genetic linkage of two markers, the apolipoprotein C1 (APOC1) gene and a cytochrome P450 (CYP2A) gene, in relation to the gene for myotonic dystrophy (DM). A peak lod score of 9. 29 at 2 cM was observed for APOC1-DM, with a lod score of 8. 55 at 4 cM for CYP2A-DM. These two markers also show close linkage to each other (theta max = 0. 05, Zmax = 9. 09). From examination of the genotypes of the recombinant individuals, CYP2A appears to map proximal to DM because in one recombinant individual CYP2A, APOC2 and CKMM had all recombined with DM. Evidence from another CYP2A-DM recombinant individual places CYP2A proximal to APOC2 and CKMM. Localisation of CYP2A on a panel of somatic cell hybrids also suggests that it is proximal to DM and APOC2/C1/E gene cluster.

