Picture of muscle from patient with multiminicore disease

Multiminicore disease consists of a spectrum of congenital neuromuscular conditions with clinical similarities such as non-progressive weakness and the presence of structural muscular changes in muscle biopsies. Muscle biopsies of patients with multiminicore disease often show variation in fiber size and occasional fiber splitting. Another muscle biopsy finding is the marked predominance of type I fibers. This condition is associated with muscular weakness and gait problems. Although multiminicore disease is usually non-progressive, a few patients experience muscle deterioration. Other medical problems may include heart disease, respiratory problems, and increased risk for malignant high blood temperature with anesthesia.

Our laboratory is interested in studying DNA and muscle biopsy samples from patients with multiminicore disease since it would provide insight into the genetic cause of their muscular condition. Identification of the genes involved in this disorder could have direct clinical benefit to patients and their families by allowing for specific diagnostic testing such as carrier detection and prenatal diagnosis for those who wish. Furthermore, understanding the genetic cause (s) of congenital myopathies will increase our understanding of muscle biology and provide insights into future development of specific treatments and therapies.

Genetics
Multiminicore disease appears to be caused by alterations in certain genes that are involved in muscle function and/or development. Multiminicore disease most often occurs in families with no previous history of neuromuscular disease. To date mutations have been found in two genes, Selenoprotein N1 (SEPN1) and Ryanodine receptor 1 (RYR1), which together account for about half the cases. A third of all multiminicore disease cases are due to mutations of the SEPN1 gene. In addition, SEPN1 mutations cause a phenotypically distinct condition called Rigid Spine Muscular Dystrophy (RSMD). RSMD and multiminicore disease due to SEPN1 mutations are also called SEPN-related myopathy. The function of selenoprotein N is yet to be determined, while ryanodine receptor regulates calcium channels. Testing for these mutations is available only on a research basis. For more information, contact us.

Research
One of the goals of the research done at the Beggs laboratory is to determine which genes and proteins are involved in the cause of multiminicore disease. We hope that what we learn will be useful for improving diagnosis and treatment of these conditions. If you are the parent of a child with this condition, if you yourself are affected, or if you are the healthcare provider of a person with multiminicore disease, you may be able to help us expand our knowledge in this condition and perhaps develop better tests, treatments and therapies.