Sex differences in the involvement of skeletal and cardiac muscles in myopathic Ano5 -/- mice.

Limb-girdle muscular dystrophy R12 (LGMD-R12) is caused by recessive mutations in the Anoctamin-5 gene ( ANO5, TMEM16E ). Although ANO5 myopathy is not X-chromosome linked, we performed a meta-analysis of the research literature and found that three-quarters of patients with LGMD-R12 are males. Females are less likely to present with moderate to severe skeletal muscle and/or cardiac pathology. Because these sex differences could be explained in several ways, we compared males and females in a mouse model of LGMD-R12. This model recapitulates the sex differences in human LGMD-R12. Only male Ano5 -/- mice had elevated serum creatine kinase after exercise and exhibited defective membrane repair after laser injury. In contrast, by these measures, female Ano5 -/- mice were indistinguishable from wild type. Despite these differences, both male and female Ano5 -/- mice exhibited exercise intolerance. Although exercise intolerance of male mice can be explained by skeletal muscle dysfunction, echocardiography revealed that Ano5 -/- female mice had features of cardiomyopathy that may be responsible for their exercise intolerance. These findings heighten concerns that mutations of ANO5 in humans may be linked to cardiac disease.