Plasma Lipids and Lipoproteins in Friedreich's Ataxia and Familial Spastic Ataxia — Evidence for an Abnormal Composition of High Density Lipoproteins

Metabolomics analysis reveals dysregulation in one carbon metabolism in Friedreich Ataxia

Friedreich Ataxia (FA) is a rare and often fatal autosomal recessive disease in which a mitochondrial protein, frataxin (FXN), is severely reduced in all tissues. With loss of FXN, mitochondrial metabolism is severely disrupted. Multiple therapeutic approaches are in development, but a key limitation is the lack of biomarkers reflecting the activity of FXN in a timely fashion. We predicted this dysregulated metabolism would present a unique metabolite profile in blood of FA patients versus Controls (Con). Plasma from 10 FA and 11 age and sex matched Con subjects was analyzed by targeted mass spectrometry and untargeted NMR. This combined approach yielded quantitative measurements for 540 metabolites and found 59 unique metabolites (55 from MS and 4 from NMR) that were significantly different between cohorts. Correlation-based network analysis revealed several clusters of pathway related metabolites including a cluster associated with one‑carbon (1C) metabolism composed of formate, sarcosine, hypoxanthine, and homocysteine. Receiver operator characteristics analyses demonstrated an excellent ability to discriminate between Con and FA with AUC values >0.95. These results are the first reported metabolomic analyses of human patients with FA. The metabolic perturbations, especially those related to 1C metabolism, may serve as a valuable biomarker panel of disease progression and response to therapy. The identification of dysregulated 1C metabolism may also inform the search for new therapeutic targets related to this pathway.

Antioxidant Therapies and Oxidative Stress in Friedreich´s Ataxia: The Right Path or Just a Diversion?

Friedreich´s ataxia is the commonest autosomal recessive ataxia among population of European descent. Despite the huge advances performed in the last decades, a cure still remains elusive. One of the most studied hallmarks of the disease is the increased production of oxidative stress markers in patients and models. This feature has been the motivation to develop treatments that aim to counteract such boost of free radicals and to enhance the production of antioxidant defenses. In this work, we present and critically review those "antioxidant" drugs that went beyond the disease´s models and were approved for its application in clinical trials. The evaluation of these trials highlights some crucial aspects of the FRDA research. On the one hand, the analysis contributes to elucidate whether oxidative stress plays a central role or whether it is only an epiphenomenon. On the other hand, it comments on some limitations in the current trials that complicate the analysis and interpretation of their outcome. We also include some suggestions that will be interesting to implement in future studies and clinical trials.

New developments in pharmacotherapy for Friedreich ataxia

Introduction: Friedreich ataxia (FRDA), a rare disease caused by the deficiency of the mitochondrial matrix protein frataxin, affects roughly 1 in 50,000 individuals worldwide. Current and emerging therapies focus on reversing the deleterious effects of such deficiency including mitochondrial augmentation and increasing frataxin levels, providing the possibility of treatment options for this physiologically complex, multisystem disorder. Areas covered: In this review article, the authors discuss the current and prior in vivo and in vitro research studies related to the treatment of FRDA, with a particular interest in future implications of each therapy. Expert opinion: Since the discovery of FXN in 1996, multiple clinical trials have occurred or are currently occurring; at a rapid pace for a rare disease. These trials have been directed at the augmentation of mitochondrial function and/or alleviation of symptoms and are not regarded as potential cures in FRDA. Either a combination of therapies or a drug that replaces or increases the pathologically low levels of frataxin better represent potential cures in FRDA.

The Role of Iron in Friedreich's Ataxia: Insights From Studies in Human Tissues and Cellular and Animal Models

Friedreich's ataxia (FRDA) is a rare early-onset degenerative disease that affects both the central and peripheral nervous systems, and other extraneural tissues, mainly the heart and endocrine pancreas. This disorder progresses as a mixed sensory and cerebellar ataxia, primarily disturbing the proprioceptive pathways in the spinal cord, peripheral nerves and nuclei of the cerebellum. FRDA is an inherited disease with an autosomal recessive pattern caused by an insufficient amount of the nuclear-encoded mitochondrial protein frataxin, which is an essential and highly evolutionary conserved protein whose deficit results in iron metabolism dysregulation and mitochondrial dysfunction. The first experimental evidence connecting frataxin with iron homeostasis came from Saccharomyces cerevisiae; iron accumulates in the mitochondria of yeast with deletion of the frataxin ortholog gene. This finding was soon linked to previous observations of iron deposits in the hearts of FRDA patients and was later reported in animal models of the disease. Despite advances made in the understanding of FRDA pathophysiology, the role of iron in this disease has not yet been completely clarified. Some of the questions still unresolved include the molecular mechanisms responsible for the iron accumulation and iron-mediated toxicity. Here, we review the contribution of the cellular and animal models of FRDA and relevance of the studies using FRDA patient samples to gain knowledge about these issues. Mechanisms of mitochondrial iron overload are discussed considering the potential roles of frataxin in the major mitochondrial metabolic pathways that use iron. We also analyzed the effect of iron toxicity on neuronal degeneration in FRDA by reactive oxygen species (ROS)-dependent and ROS-independent mechanisms. Finally, therapeutic strategies based on the control of iron toxicity are considered.

Frataxin-Mediated PINK1-Parkin-Dependent Mitophagy in Hepatic Steatosis: The Protective Effects of Quercetin

SCOPE

Naturally occurring quercetin has been found to induce mitophagy and prevent nonalcoholic fatty liver disease (NAFLD). However, it still remains elusive whether frataxin upregulation by quercetin contributes to the beneficial effect through mitophagy or not.

METHODS AND RESULTS

Adult male C57BL/J mice were fed a high-fat diet (HFD, 60% of energy from fat) with quercetin (100 mg kg-1 body weight) or not for 10 weeks. Quercetin alleviated HFD-induced histopathological changes, disorders of lipid metabolism, and mitochondrial damage. Moreover, quercetin blocked mitophagy suppression by HFD based on the increased LC3II, PTEN-induced putative kinase 1 (PINK1) and Beclin1 expressions, as well as decreased p62 levels. Quercetin also improved the Parkin translocation to mitochondria confirmed by immunofluorescence. Specifically, frataxin was lowered in the liver of HFD-fed mice or HepG2 cell incubated with oleate/palmitate but restored by quercetin, and quercetin's regulation of frataxin may depend on p53. Furthermore, lentivirus-mediated stable knockdown of frataxin in HepG2 inhibited PINK1-Parkin-associated mitophagy and resulted in lipid accumulation. Frataxin was further decreased by free fatty acids in knockdown cells concomitantly with depressed PINK1-Parkin-associated mitophagy, which was partially normalized by quercetin.

CONCLUSION

Quercetin alleviated hepatic steatosis by enhancing frataxin-mediated PINK1/Parkin-dependent mitophagy, highlighting a promising preventive strategy and mechanism for NAFLD by quercetin.

Impact of Drosophila Models in the Study and Treatment of Friedreich's Ataxia

Drosophila melanogaster has been for over a century the model of choice of several neurobiologists to decipher the formation and development of the nervous system as well as to mirror the pathophysiological conditions of many human neurodegenerative diseases. The rare disease Friedreich’s ataxia (FRDA) is not an exception. Since the isolation of the responsible gene more than two decades ago, the analysis of the fly orthologue has proven to be an excellent avenue to understand the development and progression of the disease, to unravel pivotal mechanisms underpinning the pathology and to identify genes and molecules that might well be either disease biomarkers or promising targets for therapeutic interventions. In this review, we aim to summarize the collection of findings provided by the Drosophila models but also to go one step beyond and propose the implications of these discoveries for the study and cure of this disorder. We will present the physiological, cellular and molecular phenotypes described in the fly, highlighting those that have given insight into the pathology and we will show how the ability of Drosophila to perform genetic and pharmacological screens has provided valuable information that is not easily within reach of other cellular or mammalian models.

Oxidative stress and altered lipid metabolism in Friedreich ataxia

Friedreich ataxia is a genetic disease caused by the deficiency of frataxin, a mitochondrial protein. Frataxin deficiency impacts in the cell physiology at several levels. One of them is oxidative stress with consequences in terms of protein dysfunctions and metabolic alterations. Among others, alterations in lipid metabolism have been observed in several models of the disease. In this review we summarize the current knowledge of the molecular basis of the disease, the relevance of oxidative stress and the therapeutic strategies based on reduction of mitochondrial reactive oxygen species production. Finally, we will focus the interest in alterations of lipid metabolism as a consequence of mitochondrial dysfunction and describe the therapeutic approaches based on targeting lipid metabolism.

Evidence that Charcot-Marie-Tooth disease with tremor coincides with the Roussy-Levy syndrome

Four members of a family with consanguineous relationships, the proband and his three children (2 sons and 1 daughter) are affected with Familial Spastic Ataxia and with Ehlers-Danlos' Syndrome with platelet aggregation dysfunction. In the four cases, this exceptional association appears remarkably homogeneous both in clinical and laboratory studies. The two syndromes are of dominant-autosomic transmission and probably originated in a new mutation which presumably maintained a genetic linkage. Spastic ataxia is characterized by a precocious onset and a slow evolution. The first-born son shows a dominant pyramidal syndrome with mild ataxia suggesting that it is a transitional form of familial spastic paraplegia. The Ehlers-Danlos syndrome pertains to form II or “mitis” with moderate skin hyperelasticity and joint hypermobility. The abnormal platelet aggregation curves have the same profile in all the patients. The first-born son also presents a mitral valve prolapsus as we may find either in Ehlers-Danlos syndrome or in spastic ataxia.

Abnormal activity of membrane phospholipid synthetic enzymes in the brain of patients with Friedreich's ataxia and spinocerebellar atrophy type-1

Much evidence, derived from biochemical studies of both blood and autopsied brain, has suggested that phospholipid metabolism is abnormal in patients with Friedreich's ataxia (FA), a disorder characterized by severe neuronal loss in the spinal cord and lower brain stem with no, or only modest, damage in other brain regions. To establish the cause of our recent finding of reduced brain levels of phospholipids in FA, we assayed activities of 10 phospholipid-metabolizing enzymes in the autopsied cerebellar cortex of patients with the disorder and, for comparison, in a group of patients with spinocerebellar ataxia type 1 (SCA-1), a disease characterized, unlike FA, by marked neuronal loss in the cerebellar cortex. Enzyme activities were also measured in four brain areas which are relatively unaffected morphologically in both FA and SCA-1. We found that ethanolamine kinase activity was increased in multiple brain regions of patients with FA (increased 31%-137%) and, more modestly, in SCA-1 (increased 39%-60%), suggesting a nonspecific enhancement of phosphoethanolamine production in both disorders. In contrast, the activity of phosphoethanolamine cytidylyltransferase (PECT), the rate-limiting enzyme of phosphatidylethanolamine synthesis, was significantly and markedly decreased by 35%-78% in the cerebellar, frontal, and occipital cortices of patients with FA but was normal in SCA-1. Reduced PECT activity in FA may explain the lower brain levels of phosphatidylethanolamine in the disorder. Moreover, because decreased PECT activity in FA occurs in brain regions having no, or only modest, morphologic damage, this may represent a systemic change consequent to the frataxin gene defect. Our data also suggest that therapeutic intervention in FA designed to increase synthesis of membrane phospholipids may warrant further investigation.

Brain phospholipids and fatty acids in Friedreich's ataxia and spinocerebellar atrophy type-1

Previous studies of patients with spinocerebellar atrophy type 1 (SCA-1) and Friedreich's ataxia (FA) have suggested the occurrence of membrane disturbances in both disorders. We measured concentrations of phosphatidylcholine (PC), diacyl and plasmalogen phosphatidylethanolamine (PE), and phosphatidylserine (PS), along with their fatty acid profiles, in the brains of eight patients with Friedreich's ataxia (FA) and nine patients with dominantly inherited spinocerebellar atrophy type 1 (SCA-1). Compared with the controls, levels of all phospholipid types (PE, PS, and PC) were reduced in the cerebellar but not occipital cortex of SCA-1 patients. In contrast, in the FA group, levels of PS and PE, but not PC, were reduced in both cerebellar and occipital cortices. The fatty acid composition of individual brain phospholipids was altered in both FA and SCA-1 patients, most markedly in the plasmalogen PE and PS classes of cerebellar phospholipids. Given the neuropathologic characteristics of each disorder, it is likely that altered fatty acid composition and phospholipid levels in SCA-1 cerebellar cortex occur as a consequence of pronounced cerebellar degeneration. In contrast, reduced phospholipid levels in FA cerebellar and occipital cortex, areas characterized by, at most, minimal neuronal loss in FA, may represent a widespread alteration in cellular phospholipid metabolism occurring in response to the specific gene defect in the disorder.

Friedreich's ataxia in the elderly

Friedreich's ataxia is one of the best defined and most common forms of hereditary ataxia of unknown aetiology. It is transmitted in an autosomal recessive manner, appearing sporadically, usually in childhood or adolescence. The case of an elderly patient with a possible diagnosis of late-onset Friedreich's ataxia is reported; this is thought to be the only such case in the literature. The 91-year-old Anglo female presented with ataxia that had been progressive over the last 5 years. Magnetic resonance imaging scans of the head revealed mild peripheral cerebellar atrophy and moderate cerebral atrophy. The patient's parents were unaffected but two of her six siblings had had Friedreich's ataxia starting in childhood, and four of her grandfather's siblings had had an undiagnosed illness that left them in wheelchairs early in life. Friedreich's ataxia was diagnosed in view of the strong family history and non-revealing magnetic resonance imaging of the brain.

Friedreich's ataxia: electrophysiologic and histologic findings in patients and relatives

Peripheral nerve conduction velocity and cortical evoked potentials were investigated in 48 patients with Friedreich's disease and in 35 relatives. There were 14 patients and 2 relatives who underwent sural nerve biopsy. In the patients sensory conduction velocity was moderately slowed, whereas sensory responses were markedly reduced. Nerve biopsy showed a severe loss of large myelinated fibers and no demyelination. On teased nerve fiber preparations, most fibers presented uniformly short internodes. No correlation was seen between sensory conduction findings or histologic abnormalities and clinical disability. In patients SSEP changes, which were constant, and VEPs, which were frequently involved, were unrelated to the severity or duration of clinical disability. There were 14 relatives who showed clinical signs of Friedreich's disease. Slightly decreased distal conduction velocity along sensory fibers was observed in more than half of the relatives. Nerve biopsy was noncontributory. In conclusion, we could not determine whether the abnormalities observed in the siblings were an expression of a heterozygotic condition, or whether they were early signs of the disease.

An unusual association of dentato-rubral degeneration with spinal ataxia, ophthalmoplegia and multiple cranial nerve palsies

Clinical and neuropathological data of a 50-year-old woman with an unusual multisystem degeneration are presented. Clinically the illness was characterized by progressive ataxia with ophthalmoplegia and multiple cranial nerve palsies. Neuropathological investigation showed a severe and selective degeneration of the dentato-rubral system, of the posterior columns and of several cranial nerve nuclei. The problems of differential diagnosis and classification are discussed.

Plasma cholesteryl sulfate in Friedreich's ataxia

Alteration of membrane fluidity and anomalies of membrane structural proteins have been suspected in Friedreich's ataxia. Plasma lecithin:cholesterol acyltransferase (LCAT) activity is also lowered in this disease, presumably because of a substrate effect. The membrane-stabilizing effect of cholesteryl sulfate (CS) and its inhibitory effect on LCAT activity prompted us to measure this substance in the plasma of Friedreich's ataxia patients as well as in normal subjects and in patients with Charlevoix-Saguenay disease. Plasma cholesteryl sulfate concentrations were significantly higher in Friedreich's ataxia, with levels above the upper limit of normal in nearly half of the cases. This increase was unrelated to age, sex or plasma cholesterol levels, but closely associated with the severity of the disease and thus considered to be secondary. A similar phenomenon (except the association with severity) was observed in Charlevoix-Saguenay ataxia. Levels also tended to be higher in first-degree relatives of Friedreich cases. The significance of these findings is discussed in the light of recent knowledge and experimental data obtained in this laboratory on rats made deficient in essential fatty acids. The highest concentrations of CS observed in Friedreich's ataxia (1097 micrograms/dL, 6 times the normal mean) was only 25% as high as the concentrations reported to inhibit LCAT activity.

Distribution of apolipoprotein E phenotypes in Friedreich's ataxia

Allelic polymorphism at the apolipoprotein E (apo E) gene locus (alleles epsilon 2, epsilon 3, and epsilon 4) is responsible for the existence of 6 discrete electrophoretic phenotypes of plasma apo E. Since the presence of the epsilon 2 allele in the genotype tends to be associated with higher triglyceride levels, a study was undertaken to determine if a higher frequency of this allele could account for the presence of higher plasma triglycerides in subsets of patients with Friedreich's Ataxia. The frequency of the apo E phenotypes was determined in 37 subjects with Friedreich's Ataxia and compared with that of 102 normolipidemic and 102 hyperlipidemic individuals. There was no increased prevalence of the E3/2 phenotype and the epsilon 2 allele in the Friedreich's sample as is found in a hyperlipidemic sample. Furthermore, the epsilon 2 subset did not have significantly higher plasma triglycerides than the non-epsilon 2 subset and the hypothesis was rejected. On the other hand, there was a trend for a decreased frequency of the E4/3 phenotype in the Friedreich's sample relative to the hyperlipidemic group but the difference did not reach statistical significance. The apo E phenotype distribution was also measured in a smaller sample of Charlevoix-Saguenay disease; this led to the discovery of two siblings with the relatively rare E2/2 phenotype and unexpectedly low levels of plasma lipid and lipoprotein concentrations. Plasma apolipoprotein E concentrations in both diseases were within the normal range except for subjects bearing the E2/2 phenotype.

Abnormalities of the erythrocyte membrane phospholipids in Friedreich's ataxia

The phospholipid composition and the fatty acids of the phospholipids in the erythrocyte membranes were studied in 5 patients with Friedreich's ataxia. The sphingomyelin content was found to be insignificantly reduced, that of phophatidylethanolamine was, on the contrary, increased even if non-significantly. The linoleic acid content was significantly decreased both in the total fraction of the phospholipids and in the isolated phosphatidylcholine. The relationship between the phospholipid composition and the structure and function of the membrane are discussed.

Peripheral nerve phospholipids in acrylamide neuropathy

Treatment of cats with acrylamide, either 7.5 or 15 mg/kg IM, once a day for 10 days, resulted in increases of 31 and 47% in the phospholipid content of sciatic nerve, respectively, from a control level of 41.1 +/- 2.7 mg/kg wet weight. Determination of the distribution of individual phospholipids indicated no significant differences between control cats and those receiving a cumulative dose of 150 mg/kg acrylamide. In a separate experiment, cats were treated with the 150 mg/kg dose of acrylamide and the sciatic nerve was divided into proximal and distal portions at the level of the triceps surae nerve. Significant increases in phospholipid content were observed in both the proximal and distal portions of peripheral nerve of the acrylamide-intoxicated cats. This effect was present even when the phospholipid content was expressed in terms of total protein, dry weight or total lipid. Total weight of nerve segments, however, was significantly decreased in the neuropathic animals. The data are consistent with a focal degeneration of axons with relative sparing of phospholipids.

Scanning electron microscopy studies of erythrocytes in spinocerebellar degeneration

Spinocerebellar degeneration is a heredofamilial disease of unknown aetiology. The shape of erythrocytes as revealed by scanning electron microscopy was studied in this disease. Echinocytes I, as defined by Bessis, were seen more frequently in spinocerebellar degeneration than in age and sex matched controls (7.2 +/- 1.5% in spinocerebellar degeneration, 3.4 +/- 1.2% in controls, p less than 0.001), Parkinson's disease, motor neuron disease, myopathy, and Huntington's chorea. Erythrocyte deformability was impaired to a greater extent in spinocerebellar degeneration than in the controls when the pH was raised from 7.2 to 8.0; Echinocytes I in spinocerebellar degeneration increased from 8.4 +/- 0.6 to 15.4 +/- 2.4%, in the control group from 2.8 +/- 1.2 to 13.3 +/- 2.1%. In spinocerebellar degeneration no significant correlation was found between the level of serum low density lipoprotein and the number of Echinocytes I. In both groups there was a significant correlation between the occurrence of Echinocytes I and age, and the difference of Echinocytes I was greater in aged subjects in spinocerebellar degeneration. The data suggest that membrane abnormality in erythrocytes exists in spinocerebellar degeneration and may be accelerated with the advance of age.

Tissue lipids in acute acrylamide intoxicated rats

A preliminary survey of tissue lipid composition in acrylamide intoxicated rats is reported. The animals were injected intraperitoneally with acrylamide 50 mg/kg body weight per day for 10 days. Liver cholesterol, mainly in the ester fraction, was decreased in treated rats. When fatty acid composition of liver cholesterol esters was examined, the proportions of linoleate and stearate were found to be decreased and were compensated by the increase of palmitate. Atrophy of epididymal fat pad resulted in severe triglyceride depletion and a relative increase in the proportion of phospholipids and cholesterol. There was also a reduction of linoleate, palmitate and palmitoleate in triglycerides and phospholipids of this tissue. There were, however, only minor changes in the fatty acid profile of the sciatic nerve.

Friedreich's disease 1982: etiologic hypotheses a personal analysis

The author reviews the arguments for and against the four etiologic hypotheses in Friedreich's disease that have been proposed since 1974: the "pyruvate hypothesis", the "lipid-membrane hypothesis", the "energy-defect hypothesis" and finally the "taurine hypothesis". While none of these hypotheses are mutually exclusive, the author shows that all of these mechanisms play some role in the pathophysiology of the symptoms, but that only the "taurine hypothesis" appears to be compatible with all the known facts and the biochemical abnormalities reported. The author proposed that the taurine retention defect (possibly due to a block in the high affinity-low capacity transport of taurine - The TH System) is a primary event in Friedreich's disease. Whether it is the primary genetic event still has to be determined.

Plasma lipoprotein lipase and hepatic lipase activities in Friedreich's ataxia

Plasma triglycerides although within the normal range have been shown to be higher in Friedreich's ataxia than in control subjects. To determine whether this difference could be ascribed to a reduced catabolism of triglyceride-rich lipoproteins, the activities of lipoprotein lipase (LPL) and hepatic triglyceride lipase (HL), released into plasma after an heparin injection, were measured in 13 cases of Friedreich's ataxia and 14 control subjects of comparable signs. LPL was found to be significantly lower in the ataxic patients. Moreover about half of the cases clustered below the normal range for both lipase activities. This subgroup of Friedreich's patients had significantly higher plasma triglycerides than those with normal lipase activities. Further studies are needed to relate these findings to other characteristics of the disease.

Regulation of high density lipoprotein levels

Current concepts of the structure and metabolism of high density lipoproteins are presented and factors that influence their levels in human beings are surveyed.

Lecithin: cholesterol acyltransferase activity and fatty acid composition of erythrocyte phospholipids in Friedreich's ataxia

In a study of the fatty acid composition of erythrocyte membrane phospholipids in Friedreich's ataxia, a lower percentage of linoleic acid in phosphatidylcholine was demonstrated. An enzyme involving the exchange of lipids between plasma and erythrocyte membrane, lecithin: cholesteryl acyltransferase (LCAT) was also studied. It was found that the LCAT activity had a trend towards low values. However, crossing-over studies indicated that when the LCAT enzyme of patients was exposed to its own substrate it gave low activity values but that the result reverted to normal when control substrate was used.

Friedreich's ataxia 1980. An overview of the physiopathology

Phase three of the Quebec Cooperative Study of Friedreich's Ataxia was devoted to an understanding of the physiopathology of individual symptoms on the basis of previously discovered biochemical leads. The present paper attempts to pull these results together by presenting, as a hypothesis, a unifying scheme of possible interactions and relationships. The central core of this hypothesis is the demonstration in Friedreich's ataxia of a state of mitochondrial energy deprivation. This is indirectly responsible for such associated and important symptoms as muscle weakness, dying-back neuropathy, scoliosis and hypertrophic cardiomyopathy. Secondarily, and possibly as an independent but linked-event, the entry of glucose into cells and pyruvate oxidation, are slowed down, favoring the development of diabetes. As a consequence, tissue concentrations of glutamic acid and aspartic acid are decreased, particularly in more vulnerable areas such as the cerebellum, brain stem and dorsal root ganglia. This tissue deficiency in putative excitatory neurotransmitters is directly responsible for the symptom of ataxia. This conclusion is reinforced by the correction of the ataxia in experimental animals, by the intraventricular injection of the same amino acids, and not by the injection of other stimulants of motricity. The observed mitochondrial energy deprivation could be the metabolic consequence of major changes in the linoleic acid (18.2) composition of inner mitochondrial membrane phospholipids, such as cardiolipin. Such decreases in membrane 18:2 could be the result of interference with the normal incorporation of this fatty acid to lipoproteins and/or cell membranes. It is at this level that the search for the specific enzyme defect in Friedreich's ataxia is continuing.

Friedreich's ataxia in northern Italy: I. Clinical, neurophysiological and in vivo biochemical studies

Eighteen patients with the presumptive diagnosis of Friedreich's ataxia were studied. Clinical, neurophysiological and biochemical data were concordant in 14 patients and led to the diagnosis of typical Friedreich's ataxia in this group of patients. The remaining 4 patients differed from the typical patients in several respects, but mainly in the cardiological findings. It is concluded that no single clinical or laboratory finding is typical of F.A. Multidisciplinary approaches are essential to the diagnosis of Friedreich's ataxia.

Friedreich's ataxia in the south of Italy: a clinical and biochemical survey of 23 patients

We report a clinical and biochemical survey of 23 patients with Friedreich's ataxia from southern Italy. They were studied clinically and by means of a clinical rating scale devised by us (Inherited Ataxias Clinical Rating Scale). Laboratory tests, based on the Quebec Cooperative Study, were also performed on our patients. No major clinical or biochemical differences were found between Italian and Canadian patients. Investigation of CSF monoamine metabolites showed that HVA decreased after probenecid and metoclopramide loading.

Friedreich's ataxia. I. Clinical, neurophysiological and in vivo biochemical studies

Eighteen patients with the presumptive diagnosis of Friedreich's ataxia were studied. Clinical, neurophysiological and biochemical data were concordant in 14 patients and led to the diagnosis of typical Friedreich's ataxia in this group of patients: the remaining 4 patients differed from the typical patients in several respects but mainly in the cardiological findings. It is concluded that so far no single clinical or laboratory finding is typical of F.A.. Multidisciplinary approaches are essential to the diagnosis of Friedreich's ataxia.

Specificity of biophysical and biochemical alterations in erythrocyte membranes in neurological disorders--Huntington's disease, Friedreich's ataxia, Alzheimer's disease, amyotrophic lateral sclerosis, and myotonic and duchenne muscular dystrophy

Previous studies in our laboratory had demonstrated alterations in the physical state of membrane proteins in erythrocytes in Huntington's disease. In order to assess the specificity of our findings, the results of electron spin resonance studies of protein and lipid components, scanning electron-microscopic studies, enzymatic analyses of membrane-bound sodium plus potassium stimulated, magnesium-dependent adenosine triphosphatase and protein kinase, and cell deformability studies of erythrocyte membranes have been performed in the neurological disorders, Huntington's disease, Friedreich's ataxia, Alzheimer's disease, amyotrophic lateral sclerosis, and myotonic and Duchenne muscular dystrophy. Comparison of the results revealed that alterations in the biophysical and biochemical states of erythrocyte membranes in each disorder are specific to the particular disease state with the exception of those in Friedreich's ataxia and Alzheimer's disease. In the latter instance, the clinical and pathological alterations suggest that these two diseases have different primary defects. Our studies suggest that the molecular basis of each disease is different. In addition, the results suggest that biophysical and biochemical investigations of extraneural tissue in Huntington's disease and other neurological disordes have the potential of clarifying the molecular mechanisms by which these diseases arise.

Failure to detect abnormal fatty acid profiles in serum lipoproteins in Friedreich's ataxia

A recent report indicated an association between the spinocerebellar degeneration of Friedreich's ataxia and abnormal fatty acid profiles of the cholesterol ester fraction in both total plasma and high-density lipoprotein. In an effort to substantiate these findings in lipoproteins, we estimated fatty acid profiles of total high-density lipoprotein and the cholesterol esters of high- and low-density lipoproteins. Those profiles in 10 Friedreich's ataxia patients compared well with previously reported normal values and did not differ significantly from results in 10 age-matched controls.

Lipids and lipoproteins in Friedreich's ataxia

Friedreich's ataxia is an autosomal recessively inherited disease affecting the nervous system with a high incidence of heart involvement. Abnormalities of lipid metabolism are known to be associated with several progressive ataxic conditions. In this study of 46 Friedreich's ataxia patients, serum lipids, fatty acids and lipoproteins were assayed and compared with some earlier findings on Friedreich's ataxia and related disorders. Abnormalities of low and high density lipoproteins suggestive of a major defect have been reported; in the present study the level and chemical composition of high density lipoprotein has been assessed in 20 Friedreich's ataxia patients but previous abnormalities could not be substantiated. Lipid compositional analysis of Friedreich's ataxia central nervous tissue and heart, which has not been previously reported, did not markedly differ from control tissue.

Evidence for an altered physical state of membrane proteins in erythrocytes in Friedreich's ataxia

Electron spin resonance, scanning electron microscopic, and SDS-polyacrylamide gel electrophoretic studies of erythrocytes in Friedreich's ataxia have been performed. No alteration in the physical state of membrane lipids, in morphology, or in the staining profile of erythrocytes in Friedreich's ataxia could be demonstrated. An altered conformation and/or organization of proteins in erythrocyte membranes in this disorder was suggested by spin labeling studies (P less than 0.025), favoring the possibility of a generalized membrane abnormality in Friedreich's ataxia. These findings are discussed in relation to other inherited neurological diseases where similar studies have been performed.

Hemagglutination by lectins in Friedreich's ataxia

Coded erythrocyte samples from ten individuals with Friedreich*š ataxia, from parents of five of these individuals, and from five unrelated control individuals were subjected to lecţin agglutination tests at three temperatures; before and after trypsinization; and before and after treatment with echinocyte-producing sodium salicylate and stornato^ cyte-pröducing tetracaine followed by shape-fixation with glutaraldehyde. The aġglutinins tested were the polycationic poly-L-lysirie (PLL) and four lectins with different saccharide specificities: soybean agglutinin, wheat germ agglutinin, Ufex europeus agglutinin (VEA) and concana-valin A. Altogether, over 45,000 individual test wells were scored, the status of each blood donor with respect to diagnosis being disclosed to the experimenters only after all results were tabulated.

The majority of these tests revealed no significant difference among the three groups of blood samples. A few tests did reveal statistically valid (p<0.0l) differences between groups, the most significant of which were the following: Trypsin ized control RBC were more sensitive, on average, to agglutination by VEA (fucose-inhibited) than were RBC of ataxies or their parents. Non-trypsinized control “stomatocytes” were less sensitive, on average, to agglutination by PLL than were those of ataxies or their parents. Trypsinization appeared, on average, to sensitive control but not ataxia or parent RBC to PLL-agglutination. Other differences of borderline (p-0.01-0.025) or near borderline (p = 0.025-0.05) significance were also noted. None of the statistically significant, Friedreich's ataxia-telated differences in median agglutination titers were large, the greatest being about threefold, and in every case the ranges of individual titers within the differing groups overlapped. Thus, none of these tests at present offers a method of pre clinic al diagnosis or carrier detection, and only further tests can establish whether even the differences observed in the present series of tests are reproducible.