The latest research on autism and co-morbid conditions identified a significant percentage of ASD children with Muscular Dystrophy. It was certainly something I had not come across before so I did a quick search to see what could be found that may offer additional information to this finding.
Association of Duchenne Muscular Dystrophy With Autism Spectrum Disorder
http://www.medscape.com/viewarticle/522125 (registration required)
This collaborative research from UCLA and various Boston institutions is summarised below.
“The rate of prevalence (6 of 158) was compared with the prevalence rate of autism spectrum disorder in boys in the general population (1.6 in 1000). We rejected the hypothesis that Duchenne muscular dystrophy and autism spectrum disorder co-occurrence was likely to be explained by chance (P = .006). We identify a previously unrecognized association of Duchenne muscular dystrophy with autism spectrum disorder.”
It seems clear now that association has been confirmed. The researchers offer four explanations of why this association may occur.
“The association of Duchenne muscular dystrophy with autism spectrum disorder/pervasive developmental disorder suggests several different possible mechanisms. First, there might be a specific region within the dystrophin gene that is altered, creating either a dysfunctional protein or a truncated protein.”
“Alternatively, a mutation in the dystrophin gene might be linked to a yet unidentified gene near, but not in, the dystrophin gene, accounting for the coexistence of these dual diagnoses in the same patient.”
“Still a third possible explanation might be a defect in the alternative splicing process that occurs in the central nervous system”
“A fourth explanation of the association between Duchenne muscular dystrophy and autism spectrum disorder/pervasive developmental disorder might be a defect at the protein level, especially in the extensive dystrophin-glycoprotein complex found near the cell membrane”
Added to this is the 2005 research from UCLA Department of Physiological Science.
Damage and inflammation in muscular dystrophy: potential implications and relationships with autoimmune myositis.
“Our developing understanding of the pathogenesis of muscular dystrophies and inflammatory myopathies shows complex interactions between immunological and non-immunological features of these diseases that can affect disease onset and course. Among the muscular dystrophies, the best evidence for an immunological component to disease pathogenesis exists for dystrophinopathies. Conversely, muscle damage leading to regeneration may promote some inflammatory myopathies, although much remains to be learned concerning the identity and pathological significance of non-immunological features of inflammatory myopathies. “
The Muscular Dystrophy Association has this interesting article on inflammation ..
Simply Stated . . . Inflammation
“In many disease states, the inflammatory process spins out of control and becomes harmful. In some neuromuscular diseases (like certain muscular dystrophies), inflammation is probably a secondary response to muscle degeneration, while in others (like the inflammatory myopathies), it might be a primary cause of degeneration. In either case, the inflammation can contribute to disease progression.
In Duchenne muscular dystrophy, degenerating muscle fibers are often surrounded by inflammatory cells (mostly macrophages). Although the macrophages are probably there to clear away dead tissue, they might hasten muscle decay in the process.
Severe cases of myotonic dystrophy and facioscapulohumeral MD sometimes show similar patterns of inflammation. In the inflammatory myopathies — polymyositis (PM), dermatomyositis (DM) and sporadic inclusion-body myositis (IBM) — macrophages and lymphocytes intensely invade muscle tissue.
In DM, macrophages and lymphocytes appear to attack the capillaries in muscle tissue, ultimately causing muscle fibers to degenerate by cutting off their blood supply. In PM and IBM, the immune cells actually swarm around the muscle fibers themselves, even fibers that otherwise appear healthy. The invading cells appear to directly damage muscle in PM, but it’s not clear how they contribute to muscle degeneration in IBM.
Finally, there’s some evidence of inflammation in amyotrophic lateral sclerosis, a disease caused by the death of muscle-controlling nerve cells. In some cases of ALS, the brain and spinal cord contain enhanced numbers of macrophagelike cells called microglia and elevated levels of cytokines and prostaglandin. The significance of these observations hasn’t been established.
Surprisingly, inflammation isn’t typical of myasthenia gravis or Lambert-Eaton syndrome, autoimmune diseases in which the immune system attacks the body’s own tissues.”
Italian researchers (Department of Neurosciences, Psychiatry, and Anaesthesiology, University of Messina) found an association with NFkB here at this paper ..
Activation of nuclear factor-κB in inflammatory myopathies and Duchenne muscular dystrophy
“These data indicate that nuclear factor-κB pathway is activated in polymyositis, dermatomyositis, and Duchenne muscular dystrophy. It may play a role in modulating the immune response and in regulating myogenesis and muscle repair”
Though this 2011 paper suggests otherwise…
Genetic association study of NF-κB genes in UK Caucasian adult and juvenile onset idiopathic inflammatory myopathy.
“Conclusion. An association was noted between IKBL-62T and IIM, with increased risk noted in anti-Jo-1- and -PM-Scl antibody-positive patients. However, the IKBL-62T association is dependent on TNF-308A and HLA-B*08, due to strong shared linkage disequilibrium between these alleles. After adjustment of the 8.1 HLA haplotype, NF-κB genes therefore do not independently confer susceptibility in IIM”
It certainly is another puzzling and enigmatic association between the two disorders. Certainly there seems to be once again a clear involvement of the immune system to some degree.
If anyone has some insight into this I would certainly like to here some thoughts.
Harvard 2012 research found here … http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.003322