This breakthrough research linked for the first time a known gene (capn3) and its associated protein (CAPN3) to a common form of muscular dystrophy, Limb-Girdle Muscular Dystrophy type 2A (LGMD2A). This study was also the first to reveal that a muscular dystrophy (MD) is caused by defects in a functional protein, a protein that regulates other proteins, as opposed to structural proteins that maintain muscle form. Although both the region of DNA associated with LGMD2A and capn3/CAPN3 had previously been characterized, this was the first study to show that capn3 mutations cause LGMD2A, establish detailed physical and genetic maps of the LGMD2A locus and reveal capn3 genomic features. Because no deficiency in the dystrophin-associated protein complex (composed of proteins commonly affected in MDs) was found, no specific physiological feature was known, and no appropriate animal model was available at the time, the authors mixed gene transcripts from patient muscle samples with a reference chromosome using a technique called positional cloning. This allowed identification of candidate genes that were then assayed for expression, revealing only two transcripts that localized to skeletal muscle: one was calpain-3. Its specificity for skeletal muscle and location within the 3Mb LGMD2A region established by Allamand et al (1995) via genetic linkage analysis (association between two loci in a poulation) provided strong evidence for its association with the disease.