Neuroferritinopathy


Neuroferritinopathy

Description, Causes and Risk Factors:

Neuroferritinopathy is a disorder in which iron gradually accumulates in the brain. Certain brain regions that help control movement (basal ganglia) are particularly affected. People with neuroferritinopathy have progressive problems with movement that begin at about age 40. These movement problems can include involuntary jerking motions (chorea), rhythmic shaking (tremor), difficulty coordinating movements (ataxia), or uncontrolled tensing of muscles (dystonia).

Mutations in the FTL gene cause neuroferritinopathy. The FTL gene provides instructions for making the ferritin light chain, which is one part (subunit) of a protein called ferritin. Ferritin stores and releases iron in cells. Each ferritin molecule can hold as many as 4,500 iron atoms. This storage capacity allows ferritin to regulate the amount of iron in the cells and tissues. Mutations in the FTL gene that cause neuroferritinopathy are believed to reduce ferritin's ability to store iron, resulting in the release of excess iron in nerve cells (neurons) of the brain. The cells may respond by producing more ferritin in an attempt to handle the free iron. Excess iron and ferritin accumulate in the brain, particularly in the basal ganglia, resulting in the movement problems and other neurological changes seen in neuroferritinopathy.

Neuroferritinopathy is inherited in an autosomal dominant manner with 100% penetrance. Most individuals diagnosed with neuroferritinopathy have an affected parent; the proportion of cases caused by de novo mutations is unknown. Each child of an individual with neuroferritinopathy has a 50% chance of inheriting the mutation. Prenatal testing for pregnancies at increased risk is possible if the disease-causing mutation in the family is known.

RESEARCH: Researchers studied a genetically homogeneous group of 41 subjects with the 460InsA mutation in FTL1, documenting the presentation, clinical course, biochemistry and neuroimaging. The mean age of onset was 39.4 years, beginning with chorea in 50%, focal lower limb dystonia in 42.5% and parkinsonism in 7.5%. The majority reported a family history of a movement disorder often misdiagnosed as Huntington's disease. The disease progressed relentlessly, becoming generalized over a 5-10 year period, eventually leading to aphonia, dysphagia and severe motor disability with subcortical/frontal cognitive dysfunction as a late feature. A characteristic action-specific facial dystonia was common (65%), and in 63% there was asymmetry throughout the disease course. Serum ferritin levels were low in the majority of males and post-menopausal females, but within normal limits for pre-menopausal females. MR brain imaging was abnormal on all affected individuals and one presymptomatic carrier. In conclusion, isolated parkinsonism is unusual in neuroferritinopathy, and unlike Huntington's disease, cognitive changes are absent or subtle in the early stages. Depressed serum ferritin is common and provides a useful screening test in routine practice, and gradient echo brain MRI will identify all symptomatic cases.

Symptoms:

Symptoms of the disorder may be more apparent on one side of the body than on the other. Affected individuals may also have difficulty swallowing (dysphagia) and speaking (dysarthria). Intelligence is unaffected in most people with neuroferritinopathy, but some individuals develop a gradual decline in thinking and reasoning abilities (dementia). Personality changes such as reduced inhibitions and difficulty controlling emotions may also occur as the disorder progresses.

Diagnosis:

The diagnosis of neuroferritinopathy is based on clinical findings including adult-onset chorea or dystonia and T2 weighted MRI showing excess iron storage or cystic degeneration. Molecular genetic testing for FTL, the only gene in which mutations are known to cause neuroferritinopathy, is available on a clinical basis.

Treatment:

Treatment of manifestations: Standard doses of levodopa, tetrabenazine, orphenadrine, benzhexol, sulpiride, diazepam, clonazepam, and Deanol for the movement disorder; botulinum toxin for painful focal dystonia. Prevention of secondary complications: Adequate caloric intake; physiotherapy to maintain mobility and prevent contractures. Agents/circumstances to avoid: Iron supplements are not recommended.

NOTE: The above information is for processing purpose. The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition.

DISCLAIMER: This information should not substitute for seeking responsible, professional medical care.

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