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Hyperkinetic Movement Disorders
Published in Philip B. Gorelick, Fernando D. Testai, Graeme J. Hankey, Joanna M. Wardlaw, Hankey's Clinical Neurology, 2020
Morales-Briceno Hugo, Victor S.C. Fung, Annu Aggarwal, Philip Thompson
Differential diagnosis: Other DRD syndromes: Sepiapterin deficiency, tyrosine hydroxylase deficiency, dihydropteridine reductase deficiency, 6-pyruvoyltetrahydropterin synthase deficiency, DNACJ12 mutations, PRKN mutations.7Dopamine transporter (DAT) single photon emission computed tomography (SPECT) scan may help differentiate from other forms of dystonia–parkinsonism with nigrostriatal degeneration.Diagnosis: Genetic test for GCH1 mutations (if available).CSF neurotransmitter profile: low levels of HVA, 5-HIAA, BH4, and neopterin.Dramatic and sustained response to small doses of levodopa.All patients with early-onset dystonia (<21 years) should have a trial of levodopa.
Inborn errors of metabolism
Published in Angus Clarke, Alex Murray, Julian Sampson, Harper's Practical Genetic Counselling, 2019
Prenatal diagnosis is feasible but rarely requested except for the very rare and usually fatal form of phenylketonuria, due to dihydropteridine reductase deficiency, which does not respond to the usual dietary treatment. In the classic form, due to phenylalanine hydroxylase deficiency, the enzyme is confined to the liver. There is a useful degree of genotype-phenotype correlation, so that the particular pathogenic variants found in an affected individual correlate with the disease severity and the need for dietary control. Carrier detection is feasible by mutation analysis, but prenatal diagnosis is finding significant application only in countries without effective dietary treatment. It should be borne in mind that the great majority of treated phenylketonuria patients are now entirely normal.
An update on clinical, pathological, diagnostic, and therapeutic perspectives of childhood leukodystrophies
Published in Expert Review of Neurotherapeutics, 2020
Mahmoud Reza Ashrafi, Man Amanat, Masoud Garshasbi, Reyhaneh Kameli, Yalda Nilipour, Morteza Heidari, Zahra Rezaei, Ali Reza Tavasoli
Contrast enhancement that is visible in post contrast T1W sequence (e.g. X-ALD, AxD type I, and mitochondrial disorders) [103] enlarged perivascular spaces (e.g. hypomelanosis of Ito, Mucopolysaccharidosis, Lowe syndrome, chromosomal abnormalities, PTEN mutation, and Sener syndrome) [119–122]. dystrophic calcification (e.g. AGS, RNASET2 deficient leukoencephalopathy, LCC, coates plus, ALSP, cockayne syndrome, dihydropteridine reductase deficiency, and mitochondrial disorders) [111,123,124] and megalencephaly (e.g. MLC, AxD, Canavan, and L-2-hydroxy glutaric aciduria) [109,125] are other reported special characteristics in brain MRI of individuals with leukodystrophies (Figure 4).Brain MRI has limitations and can be inconclusive in some cases. Distinguishing between genetic and acquired white matter abnormalities can be very difficult using MRI; especially in adults. Characterizing the microstructural properties of brain white matter can be a promising method for better diagnosis of leukodystrophies and assessing their prognosis. Diffusion tensor imaging (DTI) has become one of the most popular MRI techniques in brain research, which is based on the motion of water molecules [126]. This technique can provide a quantitative measurement of abnormal white matter in individuals with inherited white matter disorders [127–129]. DTI can be more sensitive than T1W, T2W, and FLAIR sequences for detecting white matter disorders and may be used for monitoring of treatment [127]. Apparent diffusion coefficient, magnetic resonance spectroscopy, and magnetization transfer imaging are other techniques used in specific types of leukodystrophies [12]. Further studies are needed to evaluate the potential of these new imaging techniques in different aspects of leukodystrophies.