comprise total of three five two and five deaf children respectively the deafness being of severe or profound degree the marriages were between first cousins s15 st and lh and between first and second cousins s19 linkage analysis of these six families resulted in individual lod scores ranging from 2 5 to 10 with polymorphic markers from the dfnb1 region d13s175 d13s141 d13s143 and d13s115 the second category of patients comprises seven new zealand families with at least two deaf siblings families 51 1160 1548 1608 1773 1873 1877 and one australian 9670 family family 1608 was atypical in that four siblings sharing the same dfnb1 marker haplotypes had a mild to moderate deafness severe at high frequency with the child of one of them being profoundly deaf in family 1873 the unrelated parents individuals ii 2 and ii 3 were deaf as well as their two children and we have therefore considered this as two families bringing to nine the total of independent families apart from families 1608 and 1873 no parent acknowledged any hearing impairment these nine families showed cosegregation between deafness and polymorphic markers of the dfnb1 region with maximum individual lod scores ranging from 0 6 to 1 2 ten other families in the original study of maw et al maw m a allen powell d r goodey r j et al the contribution of the dfnb1 locus to neurosensory deafness in a caucasian population am j hum genet 1995 57 629 35 had shown no cosegregation and one other cosegregating family was not tested for cx26.