intriguing since high levels of transgenic dystrophin or utrophin protein in skeletal muscle increase expression of the other DGC components without toxicity (Rafael et al., 1996;Rafael et al., 1994;Rafael et al., 1998). SSPN protein expression was not stoichiometric with respect to the other DGC components. This observation suggests that the molar ratio of SSPN to the other DGC components is important and that regulating the levels of SSPN within the myofiber is critical for normal muscle function. Such findings support the hypothesis that SSPN regulates protein interactions within the DGC and that increasing the stoichiometry of SSPN relative to the DGC is highly toxic. Taken together, our **data** are the first to suggest that SSPN may indeed play an important role in muscle physiology. Previous searches for patients with genetic mutations in the SSPN gene have focused on sarcoglycandeficient muscular dystrophies. Despite extensive efforts, SSPN mutations have not been identified in cases of AR-LGMD . In light of the apparent role of SSPN-mediated stability of ␣-DG and the extracellular matrix, the current report provides evidence to suggest that SSPN may also be involved in congenital muscular dystrophies.