Seven carrier and 15 non-carrier women from 16 families affected by Duchenne and Becker muscular dystrophy (DMD/DMB) were identified by quantitative PCR multiplex gene dosage. DMD/DMB patients showed 31.25% deletions and their mother carrier status was established by quantitative PCR multiplex and gene dosage analysis; no carriers of duplications were observed. X chromosome haplotypes were constructed on the maternal female relatives from both deletion and no deletion patients with dinucleotide intragenic polymorphisms D45 and SKI2 analysis; 63% of the women tested were informative in this study. After this molecular approach genetic counseling was given. thus contributing to their knowledge of risks and DMD/DMB prevention methods.