LINKAGE OF DFNB1 TO NON-SYNDROMIC NEUROSENSORY AUTOSOMAL-RECESSIVE DEAFNESS IN MEDITERRANEAN FAMILIES

Recent studies show a susceptibility locus (DFNB1) responsible for non -syndromic neurosensory autosomal-recessive deafness (NSRD) mapping to the pericentromeric region of chromosome 13q, In order to better unde rstand the frequency with which DFNB1 is the gene for deafness in our patient population and the role of DFNB1 in Caucasians, we performed a genetic linkage study with four microsatellite markers linked to DFNB 1 in a total of 48 independent Mediterranean families, of which 30 and 18 were of Italian and Spanish descent, respectively. A maximum two-p oint lod score of 7.28 was found with marker D13S115 at a recombinatio n frequency of Theta 0.1. Significant lod scores were also obtained fo r D13S143, D13S292 and D13S175. Genetic heterogeneity was confirmed us ing the HOMOG program which indicated absence of linkage to DFNB1 in a pproximately 21% of the sample. This study clearly demonstrates that D FNB1 plays an important role in 79% of Mediterranean families with NSR D. Furthermore, results from multipoint analysis predict that the DFNB 1 gene maps between markers D13S175 and D13S115 which are separated by approximately 14.2 cM.