Lariat branch point mutation in the dysferlin gene with mild limb-girdle muscular dystrophy

The authors report a genotype-phenotype correlation in a limb-girdle muscular dystrophy 2B family. Two severely affected sisters were homozygous for a dysferlin null mutation. Their mildly affected compound heterozygous mother harbored, in addition to one null allele, an in-frame exon-skipping allele caused by a novel lariat branch point mutation. The dysferlin molecule arising from the latter allele appeared to partially complement the null mutation, likely accounting for the mother's mild phenotype.