THE GENE FOR MESOMELIC DYSPLASIA KANTAPUTRA TYPE IS MAPPED TO CHROMOSOME 2Q24-Q32

Mesomelic dysplasia Kantaputra type (MDK) (MIM 156232) is a new autos omal dominant skeletal dysplasia characterized by dwarfism, shortening of the forearms/lower-legs, carpal/tarsal synostosis, and dorsolatera l foot deviation. We studied a Thai family in which 15 members in 3 ge nerations were affected with MDK. With reference to the breakpoints of a balanced translocation [t(2;8)(q31;p21)] in patients from a previou sly reported Italian family with a skeletal dysplasia that appears sim ilar to MDK, a linkage analysis was performed in the Thai family using 50 CA-repeat markers mapped to nearby regions (2q22-q34 and 8p24-p21) of the translocation breakpoints. The results clearly ruled out a lin kage of MDK to marker loci at the Sp24-p21 region, whereas all nine af fected members available for the study shared a haplotype at four loci (D2S2284, D2S326, D2S2188, and D2S2314) spanning about 22.7 cM in the 2q24-q32 region. The computer-assisted two-point linkage analysis rev ealed maximum logarithm of odds (lod) scores of 4.82, 4.21, 4.82, and 4.21 (theta = 0) at these loci, respectively. These data indicated tha t the MDK locus is in the vicinity of D2S2284 and D2S2188 loci that ar e most likely mapped to 2q24-q32.