ASSIGNMENT OF THE HUMAN MOESIN GENE (MSN) TO CHROMOSOME REGION XQ11.2-]Q12

The human moesin gene (MSN) was mapped to the long arm of the X chromo some. PCR products for the moesin gene cDNA were used as probes to iso late their corresponding cosmid clones. Fluorescence in situ hybridiza tion (FISH) with two of the isolated cosmid probes showed signals at X q11.2 --> q12, whereas four other cosmids showed FISH signals on chrom osome 5. Southern blot hybridization, using a PCR product correspondin g to the 3' region of the moesin gene cDNA as a probe (probe-3), on on e of the two cosmids that produced signals on the X chromosome gave 5. 7- and 3.5-kb HindIII fragments. Further Southern hybridization of the DNA from XY, XX, and XXXXX individuals using probe-3 revealed a gene- dose effect of the X chromosome on the size of a 3.5-kb and a 3.0-kb H indlll fragment; in contrast, an invariant 9.8-kb band was present in the DNA of all individuals tested. Sequencing of an exon-intron border revealed that the two cosmids had predicted sequences. These results indicated that the two cosmids contained MSN, and it was consequently assigned to human chromosome region Xq11.2 --> q12. These results stro ngly suggest that MSN may be removed from candidacy for Wiskott-Aldric h syndrome, which has been putatively mapped to Xp11.3 --> p11.22.