GENETIC-MAPPING OF THE CLEIDOCRANIAL DYSPLASIA (CCD) LOCUS ON CHROMOSOME BAND 6P21 TO INCLUDE A MICRODELETION

Cleidocranial dysplasia (CCD) is a generalized skeletal dysplasia with autosomal dominant inheritance. Recently, the CCD disease locus was localized to 23 Mundlos et al., 1995 and 17 cM regions Feldman et al., 1995 , of chromosome band 6p21 by linkage studies of seven afflicted families. Of note, the 23 cM region contained a microdeletion detected in one family at D6S459, an interval that was excluded in the 17 cM overlapping region. Here, linkage of CCD to 6p21 was independently confirmed with a maximal two-point LOD score of Z=5.12 with marker D6S452 at theta=0.00. Recombinant events in two affected individuals defined a CCD region of 7 cM from D6S465 to D6S282, which overlapped with the CCD region containing the microdeletion but did not overlap with the 17 cM critical region from D6S282 to D6S291. These results suggest the refined localization of the CCD region to 6 cM spanning markers D6S438 to D6S282, thereby reviving the possibility that the CCD gene lies within the microdeletion at D6S459.