Rat animal models are widely used owing to their relatively superior cognitive abilities and higher similarity compared with mouse models to human physiological characteristics. However, their use is limited because of difficulties in establishing embryonic stem cells and performing genetic modifications, and insufficient embryological research. In this study, we established optimal superovulation and fertilized-egg transfer conditions, including optimal hormone injection concentration (≥150 IU/kg of PMSG and hCG) and culture medium (mR1ECM), to obtain high-quality zygotes and establish in vitro fertilization conditions for rats. Next, sgRNA with optimal targeting activity was selected by performing PCR analysis and the T7E1 assay, and the CRISPR/Cas9 system was used to construct a rat model for muscular dystrophy by inducing a deficiency in the fukutin gene without any off-target effect detected. The production of fukutin knockout rats was phenotypically confirmed by observing a drop-in body weight to one-third of that of the control group. In summary, we succeeded in constructing the first muscular dystrophy disease rat model using the CRISPR/CAS9 system for increasing future prospects of producing various animal disease models and encouraging disease research using rats.

Mutations in the fukutin gene were first identified in Japanese patients with classic Fukuyama congenital muscular dystrophy, a severe form of congenital muscular dystrophy associated with cobblestone lissencephaly and ocular defects. Patients of different ethnicities and with milder phenotypes, including limb girdle muscular dystrophy and cardiomyopathy without brain impairment, have also been reported. The hallmark of this disorder, regardless of the clinical outcome, is moderate-to-severe hypoglycosylation of alpha-dystroglycan in muscle sections. We describe the case of a boy harboring two novel mutations in fukutin gene and presenting a five-year history of asymptomatic hyperCKemia, without overt muscle, brain or ocular involvement. Genetic investigations, guided by the presence of moderate myopathic changes on muscle biopsy with loss of immunodetectable alpha-dystroglycan, led to a definitive diagnosis. Cardiac and echocardiographic examinations at follow-up disclosed low normal left ventricular function but no active cardiovascular symptoms. We suggest that fukutin mutations should be sought in asymptomatic hyperCKemia and subclinical heart dysfunction.