A phase I trial of adeno-associated virus serotype 1-γ-sarcoglycan gene therapy for limb girdle muscular dystrophy type 2C

gamma-Sarcoglycanopathy or limb girdle muscular dystrophy type 2C is an untreatable disease caused by autosomal recessively inherited mutations of the gamma-sarcoglycan gene. Nine non-ambulatory patients (two males, seven females, mean age 27 years; range 16-38 years) with del525T homozygous mutation of the gamma-sarcoglycan gene and no gamma-sarcoglycan immunostaining on muscle biopsy were divided into three equal groups to receive three escalating doses of an adeno-associated virus serotype 1 vector expressing the human gamma-sarcoglycan gene under the control of the desmin promoter, by local injection into the extensor carpi radialis muscle. The first group received a single injection of 3 x 10(9) viral genomes in 100 mu l, the second group received a single injection of 1.5 x 10(10) viral genomes in 100 mu l, and the third group received three simultaneous 100-mu l injections at the same site, delivering a total dose of 4.5 x 10(10) viral genomes. No serious adverse effects occurred during 6 months of follow-up. All nine patients became adeno-associated virus serotype 1 seropositive and one developed a cytotoxic response to the adeno-associated virus serotype 1 capsid. Thirty days later, immunohistochemical analysis of injected-muscle biopsy specimens showed gamma-sarcoglycan expression in all three patients who received the highest dose (4.7-10.5% positively stained fibres), while real-time polymerase chain reaction detected gamma-sarcoglycan messenger RNA. In one patient, gamma-sarcoglycan protein was detected by western blot. For two other patients who received the low and intermediate doses, discrete levels of gamma-sarcoglycan expression (< 1% positively stained fibres) were also detectable. Expression of gamma-sarcoglycan protein can be induced in patients with limb girdle muscular dystrophy type 2C by adeno-associated virus serotype 1 gene transfer, with no serious adverse effects.