GENETIC-MAPPING OF THE KALLMANN SYNDROME AND X-LINKED OCULAR ALBINISMGENE LOCI

The X linked form of Kallmann syndrome (KAL) and X linked ocular albin ism (OA1) have both been mapped to Xp22.3. We have used a dinucleotide repeat polymorphism at the Kallmann locus to type 17 X linked ocular albinism families which had previously been typed for the Xg blood gro up (XG) and the DNA markers DXS237 (GMGX9), DXS143 (dic56), and DXS85 (782). Close linkage was found between KAL and OA1 with a maximum lod score (Zmax) of 30.14 at a recombination fraction (thetamax) of 0.06 ( confidence interval for theta: 0.03-0.10). KAL was also closely linked to DXS237 (Zmax=15.32; thetamax=0.05; Cl 0.02-0.12) and DXS143 (Zmax= 14.57; thetamax 0.05; CI 0.02-0.13). There was looser linkage to the X g blood group (XG) and to DXS8S (782). Multipoint linkage analysis gav e the map: -0.025-KAL-0.025-DXS143-0.015-OA1-0.09-DXS85-Xcen. Placemen t of OA1 proximal to DXS143 was supported by odds of 2300:1 compared t o other orders. This confirms our previous localisation of OA1 and imp roves the genetic mapping of both disease loci.