Ischaemic forearm testHot
Investigations in Child Neurology 4752 0
This test measures basal and post-exercise venous lactate and ammonia levels. The blood lactate is measured after the fist has been clenched repeatedly for 1 minute with the arm made ischaemic using a sphygmomanometer. Samples are taken at -10 minutes (pre-exercise) and at 0, 1, 3, 5, 10 and 20 minutes following release of the cuff. A normal response is characterized by a lactate increase of 3-5 fold over baseline with a peak at 1-3 minutes post-exercise, while ammonia increases 5-10 fold over the same time. An absent or inadequate (less than 1.5-fold) increase in lactate is...
Investigations in Child Neurology 2089 0
This is a method for stressing the pterin system, but may be unreliable. It was developed as a biochemical marker for pterin synthesis defects associated with dopamine-responsive dystonia, especially GTP-CH deficiency. A dose of 100mg/kg of phenylalanine is used. A phenylalanine/tyrosine ratio >7.5 is suggestive, but not diagnostic, of a pterin synthesis defect. The phenylalanine must rise above 600umol/l. for the test to be valid. This test has low sensitivity and specificity.
Cholesterol ester traffickingHot
Investigations in Child Neurology 2329 0
Employed for definitive diagnosis of Niemann-Pick type C phenotype.
Very Long Chain Fatty AcidsHot
Investigations in Child Neurology 2092 0
Usually done in peroxisomopathies, but essential for diagnosis of DBP deficiency when plasma studies are normal.
Investigating Fatty Acid Oxidation disordersHot
Investigations in Child Neurology 2323 0
Also clinically heterogeneous but urinary organic acid and plasma carnitine and acylcarnitine studies will prompt this evaluation
Investigating Pyruvate DehydrogenaseHot
Investigations in Child Neurology 2487 0
Clinically heterogeneous, including neonatal hypotonia and epileptic seizures, Leigh and Leigh-like syndromes, episodic ataxia and paroxysmal dystonia. Lactates may be normal Basal ganglia abnormality (especially globus pallidus) may be a clue.
Fibrolblast culture studiesHot
Investigations in Child Neurology 1905 0
The storage of cultured fibroblasts, like the retention of DNA samples, is one of the prerequisites for later genetic diagnosis of unexplained disorders. Some types of fibroblast study are particularly important
Investigating Golgi and Endoplasmic Reticulum DisordersHot
Investigations in Child Neurology 2687 0
Golgi and endoplasmic reticulum disorders (congenital defects of glycosylation) Attaching sugar molecules to proteins or lipids (glycosylation) is mediated by the Golgi apparatus or complex and by the endoplastic reticulum and is necessary for numerous biochemical functions. Defects may be divided into soluble and structural abnormalities. The 'soluble' congenital defects of glycosylation (CDG) - predominantly defects of N-glycosylation - are many and increasing in number but by far the most important is CDG1a. 'structural' defects of O-glycosylation comprise congenital and later onset muscular dystrophies and are investigated by completely different...
Investigating Peroxisomal DisordersHot
Investigations in Child Neurology 4085 0
Peroxisomes are spherical 1pm diameter organelles with a multitude of oxidative and other enzymes packed within a single-layered membrane (http://www.peroxisomedb. org) global' peroxisomal disorders with impaired peroxisomal biogenesis (fewer or even no peroxisomes), together with those single peroxisomal enzyme defects that induce a similar phenotype (in particular, D-bifunctional protein deficiency) adrenoleukodystrophy, due to an X-linked defect of the peroxisomal ABCD1 gene that codes for the peroxisomal membrane protein ABCD1, a member of the ATP-hmding cassette transporters. While estimation of very...
Investigating Mitochondrial DisordersHot
Investigations in Child Neurology 4616 0
Mitochondrial disorders With the explosion of knowledge about disorders of the mitochondria, definitive investigations have become more complex and specialized. However, clinical clues can point towards a mitochondrial disorder and fairly simple tests support the diagnosis sufficiently to proceed to specific investigations of mitochondrial function. To a certain extent there is a relationship between the type of disease and the site of metabolic defect along the pathway from the inner mitochondrial membrane to the termination of the respiratory chain, but there is considerable heterogeneity. It has long been known that most of the...