What is IBMPFD?
IBMPFD is an uncommon, adult-onset disorder that has been studied in over two dozen families from the U.S. and other countries. Affected individuals may show one or a combination of the three involved conditions. Approximately 90% of the affected persons in the study have myopathy or muscle weakness, particularly of the shoulder and hip girdles, that can lead to loss of walking ability and even death by complications of respiratory and cardiac failure. About half of affected study participants have Paget disease of bone characterized by abnormal rates of bone growth that can result in bone pain, enlargement and fractures. Findings of premature Frontotemporal Dementia affecting behavior and personality are seen in a quarter to a third of affected individuals.
In 2003, the Kimonis group identified the gene causing IBMPFD as Valosin-Containing Protein, or VCP (also called CDC48 and p97). This work was published in Nature Genetics 2004.36: 377-381. An evolutionary old gene, VCP is common to basic life forms, and is involved in several vital cellular processes. The lab found that six possible mutations in the VCP gene resulted in IBMPFD. Furthermore, there appeared to be a mutation "hot-spot"; that is to say, the majority of the mutations are found in the same region within VCP.
Now that IBMPFD has been clinically and genetically characterized, the next step towards developing potential treatments is identifying the specific ways in which the VCP mutations affect patients at the cellular level. Dr. Giles Watts and others in the Kimonis lab with funding from the MDA and NIH are currently working on molecular genetics experiments that will aid in deciphering the mechanisms within the cell that are at the root of IBMPFD.