Pantothenate kinase-associated neurodegeneration (PKAN), formerly called Hallervorden–Spatz syndrome, is a genetic degenerative disease of the brain that can lead to parkinsonism, dystonia, dementia, and ultimately death. Neurodegeneration in PKAN is accompanied by an excess of iron that progressively builds up in the brain. PKAN is caused by loss of function of the enzyme PANK2, due to bi-allelic genetic mutations. It follows autosomal recessive inheritance. This enzyme is the first step in the pathway converting vitamin B5 into coenzyme A. There are currently no treatments that modify disease progress, though there are a number of medications and therapies that can help improve symptoms and there is active research into treatments. Signs and symptoms
Symptoms typically begin in childhood and are progressive, often resulting in death by early adulthood. Symptoms of PKAN begin before middle childhood, and most often are noticed before ten years of age. Symptoms include:
dystonia (repetitive uncontrollable muscle contractions that may cause jerking or twisting of certain muscle groups)
dysphagia & dysarthria due to muscle groups involved in speech being involved
rigidity/stiffness of limbs
tremor
writhing movements
dementia
spasticity
weakness
seizures (rare)
toe walking
retinitis pigmentosa, another degenerative disease that affects the individuals retina, often causing alteration of retinal color and progressive deterioration of the retina at first causing night blindness and later resulting in a complete loss of vision.25% of individuals experience an uncharacteristic form of PKAN that develops post-10 years of age and follows a slower, more gradual pace of deterioration than those pre-10 years of age.
Neuropathology
Microscopic features of PKAN include high levels of iron in the globus pallidus and the pars reticulata of substantia nigra, evident as a characteristic rust-brown discoloration in a pattern called the eye-of-the-tiger sign; lipofuscin and neuromelanin concentrated in the iron-accumulating areas; oval, nonnucleated structures representing swollen axons whose cytoplasm swells with vacuoles, referred to as spheroids, axon schollen, or neuroaxonal dystrophy; and Lewy bodies. Treatment
Phosphopantothenate has been shown to treat PKAN in a human, and also in a mouse model of the disease. Pantethine (a precursor of pantetheine) has been studied and shown to be effective in a mouse and in a fruit fly model of the disease. Prognosis
Survival rates for those diagnosed with typical PKAN, and left untreated is 11.18 years with a standard deviation of 7.8 years. A study reporting good outcomes in a single patient with late onset PKAN has been performed. Epidemiology
Prevalence data regarding this disorder remains incomplete, however it is estimated that anywhere between 1 in 1,000,000 to 3 in 1,000,000 individuals will be affected by this disorder (based upon observed cases in a population), but once again this is only an estimate as the disease is so rare it is difficult to statistically and accurately ascertain. History
PKAN was first described by Hallervorden and Spatz (1922). Their discovery was brought about by a diagnosis of a family of 12 in which five sisters exhibited progressively increasing dementia and dysarthria. Autopsies revealed brown discolorations in different areas of the brain (particularly of interest were the globus pallidus and substantia nigra regions).