These individuals face significant speech deficits as well as psychiatric and behavioral disturbances.Being a progressive, degenerative nerve illness, PKAN leads to early immobility and often death by early adulthood. Death occurs prematurely due to infections such as pneumonia, and the disease in itself is technically not life limiting. Genetics
PKAN is an autosomal recessive disorder. Both the parents of an affected child must be heterozygous carriers for the disease and therefore must carry one mutant allele. As it is an autosomal disorder, those heterozygous for the disorder may not display any atypical characteristics that are considered suggestive of the disorder, however there have been reported cases of compound heterozygosity in which heterozygous individuals do develop the classic form of the disease.The disorder is caused by a mutant PANK2 gene located at the chromosomal locus: 20p13-p12.3. PANK2 is responsible for coding the protein Pantothenate kinase 2. PANK2 encodes the enzyme pantothenate kinase, and mutations in the gene lead to an inborn error of vitamin B5 (pantothenate) metabolism. Vitamin B5 is required for the production of coenzyme A in cells. Disruption of this enzyme affects energy and lipid metabolism and may lead to accumulation of potentially harmful compounds in the brain, including iron.PANK2 encodes a 1.85Kb transcript which is derived from seven exons covering a total distance of approximately 3.5Mb of genomic DNA. The PANK2 gene also encodes a 50.5-kDaprotein that is a functional pantothenate kinase, an essential regulatory enzyme in coenzyme A (CoA) biosynthesis, and catalyzing the phosphorylation of pantothenate (vitamin B5), N-pantothenoyl-cysteine, and pantetheine (OMIM).
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).