CHMP2B-related frontotemporal dementia
A rare, progressive brain disorder caused by mutations in the CHMP2B gene, typically presenting in the 50s‑60s with personality, behavior, and language changes and a survival of 3–21 years after symptom onset.
Overview
CHMP2B-related frontotemporal dementia is a progressive brain disorder that affects personality, behavior, and language. The symptoms usually become noticeable in a person's fifties or sixties, and affected individuals survive about 3 to 21 years after the appearance of symptoms.
Symptoms
Early behavioral changes
- Inappropriate emotional responses
- Restlessness
- Loss of initiative
- Neglect of personal hygiene
- Hyperorality (overeating sweet foods or placing non‑food items in the mouth)
- Difficulty interacting socially in an appropriate manner
- Increasing need for assistance with personal care and activities of daily living
Speech and language problems (aphasia)
- Progressive difficulty speaking while often retaining comprehension of spoken and written language
- Difficulty using numbers (dyscalculia)
- Eventual loss of the ability to communicate in later stages
Movement abnormalities (later stage)
- Rigidity
- Tremors
- Uncontrolled muscle tensing (dystonia)
- Involuntary muscle spasms (myoclonus)
- Loss of ability to walk as disease progresses
Frequency
CHMP2B-related frontotemporal dementia has been reported in one large family in Denmark and a few unrelated individuals from other countries. This disease appears to be a rare form of frontotemporal dementia.
Causes & Risk Factors
Mutations in the CHMP2B gene cause this disorder. The gene provides instructions for making the protein charged multivesicular body protein 2B, which is active in the brain and plays an essential role in transporting proteins destined for degradation.
Most disease‑causing mutations produce an abnormal protein missing a critical segment that normally keeps the protein inactive when not needed. Without this segment, the protein remains constantly active, disrupting transport and degradation of other proteins and ultimately leading to neuronal death.
A gradual loss of neurons throughout the brain, especially in the frontal and temporal lobes, characterizes the disease. The frontal lobes are involved in reasoning, planning, judgment, and problem‑solving, while the temporal lobes process hearing, speech, memory, and emotion. The reason why symptoms are primarily linked to these regions remains unclear.
Inheritance
This condition is inherited in an autosomal dominant manner, meaning one copy of the altered gene in each cell is sufficient to cause the disorder.
Other Names for This Condition
- Chromosome 3‑linked frontotemporal dementia
- DTM1
- FTD-3
- FTD‑CHMP2B
- FTD3
Additional Information & Resources
Genetic Testing Information
- Genetic Testing Registry: Frontotemporal dementia and/or amyotrophic lateral sclerosis 7
Genetic and Rare Diseases Information Center
- Frontotemporal dementia
Patient Support and Advocacy Resources
- National Organization for Rare Disorders (NORD)
Catalog of Genes and Diseases from OMIM
- FRONTOTEMPORAL DEMENTIA AND/OR AMYOTROPHIC LATERAL SCLEROSIS 7; FTDALS7
Scientific Articles on PubMed
- PubMed
References
- Brown J, Ashworth A, Gydesen S, Sorensen A, Rossor M, Hardy J, Collinge J. Familial non‑specific dementia maps to chromosome 3. Hum Mol Genet. 1995 Sep;4(9):1625‑8. doi:10.1093/hmg/4.9.1625.
- Brown J, Gydesen S, Johannsen P, et al. Frontotemporal dementia linked to chromosome 3. Dement Geriatr Cogn Disord. 2004;17(4):274‑6. doi:10.1159/000077153.
- Brown J. Chromosome 3‑linked frontotemporal dementia. Cell Mol Life Sci. 1998 Sep;54(9):925‑7. doi:10.1007/s000180050222.
- Gydesen S, Brown JM, Brun A, et al. Chromosome 3 linked frontotemporal dementia (FTD‑3). Neurology. 2002 Nov 26;59(10):1585‑94. doi:10.1212/01.wnl.0000034763.54161.1f.
- Holm IE, Englund E, Mackenzie IR, et al. A reassessment of the neuropathology of frontotemporal dementia linked to chromosome 3. J Neuropathol Exp Neurol. 2007 Oct;66(10):884‑91. doi:10.1097/nen.0b013e3181567f02.
- Lindquist SG, Braedgaard H, Svenstrup K, et al. Frontotemporal dementia linked to chromosome 3 (FTD‑3) – current concepts and the detection of a previously unknown branch of the Danish FTD‑3 family. Eur J Neurol. 2008 Jul;15(7):667‑70. doi:10.1111/j.1468-1331.2008.02144.x.
- Roos P, Holm IE, Nielsen JE, et al. CHMP2B‑Related Frontotemporal Dementia‑Amyotrophic Lateral Sclerosis. GeneReviews® (2027). Available from: http://www.ncbi.nlm.nih.gov/books/NBK1199/
- Skibinski G, Parkinson NJ, Brown JM, et al. Mutations in the endosomal ESCRTIII‑complex subunit CHMP2B in frontotemporal dementia. Nat Genet. 2005 Aug;37(8):806‑8. doi:10.1038/ng1609.
- van der Zee J, Urwin H, Engelborghs S, et al. CHMP2B C‑truncating mutations in frontotemporal lobar degeneration are associated with an aberrant endosomal phenotype in vitro. Hum Mol Genet. 2008 Jan 15;17(2):313‑22. doi:10.1093/hmg/ddm309.