Publication details

ISPD gene mutations are a common cause of congenital and limb-girdle muscular dystrophies

Authors	CIRAK Sebahattin FOLEY Aileen Reghan HERRMANN Ralf WILLER Tobias YAU Shu STEVENS Elizabeth TORELLI Silvia BRODD Lina KAMYNINA Alisa VONDRÁČEK Petr ROPER Helen LONGMAN Cheryl KORINTHENBERG Rudolf MARROSU Gianni NUERNBERG Peter MICHELE Daniel E PLAGNOL Vincent HURLES Matt MOORE Steven A SEWRY Caroline A CAMPBELL Kevin P VOIT Thomas MUNTONI Francesco
Year of publication	2013
Type	Article in Periodical
Magazine / Source	Brain
MU Faculty or unit	Faculty of Medicine
Citation
Doi	http://dx.doi.org/10.1093/brain/aws312
Field	Neurology, neurosurgery, neurosciences
Keywords	congenital muscular dystrophy; limb-girdle muscular dystrophy; dystroglycan; laminin; isoprenoid synthase
Description	Dystroglycanopathies are a clinically and genetically diverse group of recessively inherited conditions ranging from the most severe of the congenital muscular dystrophies, Walker-Warburg syndrome, to mild forms of adult-onset limb-girdle muscular dystrophy. Their hallmark is a reduction in the functional glycosylation of alpha-dystroglycan, which can be detected in muscle biopsies. An important part of this glycosylation is a unique O-mannosylation, essential for the interaction of alpha-dystroglycan with extracellular matrix proteins such as laminin-alpha 2. Mutations in eight genes coding for proteins in the glycosylation pathway are responsible for similar to 50% of dystroglycanopathy cases. Despite multiple efforts using traditional positional cloning, the causative genes for unsolved dystroglycanopathy cases have escaped discovery for several years. In a recent collaborative study, we discovered that loss-of-function recessive mutations in a novel gene, called isoprenoid synthase domain containing (ISPD), are a relatively common cause of Walker-Warburg syndrome. In this article, we report the involvement of the ISPD gene in milder dystroglycanopathy phenotypes ranging from congenital muscular dystrophy to limb-girdle muscular dystrophy and identified allelic ISPD variants in nine cases belonging to seven families. In two ambulant cases, there was evidence of structural brain involvement, whereas in seven, the clinical manifestation was restricted to a dystrophic skeletal muscle phenotype. Although the function of ISPD in mammals is not yet known, mutations in this gene clearly lead to a reduction in the functional glycosylation of alpha-dystroglycan, which not only causes the severe Walker-Warburg syndrome but is also a common cause of the milder forms of dystroglycanopathy.