Inheritance of DMD mutation, parental origin of most inactivated X-chromosome and familial skewed XCI in family of subject #1. A) Family pedigree. Haplotype analysis of Xp21 locus indicates that the mutation is located at the paternal X-chromosome. B) Genemapper traces of non-digested and Hpa II digested AR alleles in blood. Methylated status of the AR revealed that both mother and daughter present highly skewed XCI. Maternal X-chromosome is preferentially inactivated in affected daughter indicating that the paternal X-chromosome carrying the DMD mutated allele is active.