In vitro modeling of dendritic atrophy in Rett syndrome: determinants for phenotypic drug screening in neurodevelopmental disorders.

Dendritic atrophy, defined as the reduction in complexity of the neuronal arborization, is a hallmark of several neurodevelopmental disorders, including Rett Syndrome (RTT). RTT, affecting 1:10,000 girls worldwide, is mainly caused by mutations in the MECP2 gene and has no cure. We describe here an in vitro model of dendritic atrophy in Mecp2-/y mouse hippocampal primary cultures, suitable for phenotypic drug-screening. Using High-Content Imaging techniques, we systematically investigated the impact of culturing determinants on several parameters such as neuronal survival, total dendritic length, dendritic endpoints, soma size, cell clusterization, spontaneous activity. Determinants included cell-seeding density, glass or polystyrene substrates, coating with poly-Ornithine with/without Matrigel and miniaturization from 24 to 96-half surface multiwell plates. We show that in all plate-sizes at densities below 320 cells/mm2, morphological parameters remained constant while spontaneous network activity decreased according to the cell-density. Mecp2-/y neurons cultured at 160 cells/mm2 density in 96 multiwell plates, displayed significant dendritic atrophy and showed a marked increase in dendritic length following treatment with Brain-derived neurotrophic factor (BDNF) or Mirtazapine. In conclusion, we have established a phenotypic assay suitable for fast screening of hundreds of compounds, which may be extended to other neurodevelopmental diseases with dendritic atrophy.

Effects of oral administration of common antioxidant supplements on the energy metabolism of red blood cells. Attenuation of oxidative stress-induced changes in Rett syndrome erythrocytes by CoQ10.

Nutritional supplements are traditionally employed for overall health and for managing some health conditions, although controversies are found concerning the role of antioxidants-mediated benefits in vivo. Consistently with its critical role in systemic redox buffering, red blood cell (RBC) is recognized as a biologically relevant target to investigate the effects of oxidative stress. In RBC, reduction of the ATP levels and adenylate energy charge brings to disturbance in intracellular redox status. In the present work, several popular antioxidant supplements were orally administrated to healthy adults and examined for their ability to induce changes on the energy metabolism and oxidative status in RBC. Fifteen volunteers (3 per group) were treated for 30 days per os with epigallocatechin gallate (EGCG) (1 g green tea extract containing 50% EGCG), resveratrol (325 mg), coenzyme Q10 (CoQ10) (300 mg), vitamin C (1 g), and vitamin E (400 U.I.). Changes in the cellular levels of high-energy compounds (i.e., ATP and its catabolites, NAD and GTP), GSH, GSSG, and malondialdehyde (MDA) were simultaneously analyzed by ion-pairing HPLC. Response to oxidative stress was further investigated through the oxygen radical absorptive capacity (ORAC) assay. According to our experimental approach, (i) CoQ10 appeared to be the most effective antioxidant inducing a high increase in ATP/ADP, ATP/AMP, GSH/GSSG ratio and ORAC value and, in turn, a reduction of NAD concentration, (ii) EGCG modestly modulated the intracellular energy charge potential, while (iii) Vitamin E, vitamin C, and resveratrol exhibited very weak effects. Given that, the antioxidant potential of CoQ10 was additionally assessed in a pilot study which considered individuals suffering from Rett syndrome (RTT), a severe X-linked neuro-developmental disorder in which RBC oxidative damages provide biological markers for redox imbalance and chronic hypoxemia. RTT patients (n = 11), with the typical clinical form, were supplemented for 12 months with CoQ10 (300 mg, once daily). Level of lipid peroxidation (MDA production) and energy state of RBCs were analyzed at 2 and 12 months. Our data suggest that CoQ10 may significantly attenuate the oxidative stress-induced damage in RTT erythrocytes.

L-Serine dietary supplementation is associated with clinical improvement of loss-of-function GRIN2B-related pediatric encephalopathy.

Autosomal dominant mutations in GRIN2B are associated with severe encephalopathy, but little is known about the pathophysiological outcomes and any potential therapeutic interventions. Genetic studies have described the association between de novo mutations of genes encoding the subunits of the N-methyl-d-aspartate receptor (NMDAR) and severe neurological conditions. Here, we evaluated a missense mutation in GRIN2B, causing a proline-to-threonine switch (P553T) in the GluN2B subunit of NMDAR, which was found in a 5-year-old patient with Rett-like syndrome with severe encephalopathy. Structural molecular modeling predicted a reduced pore size of the mutant GluN2B-containing NMDARs. Electrophysiological recordings in a HEK-293T cell line expressing the mutated subunit confirmed this prediction and showed an associated reduced glutamate affinity. Moreover, GluN2B(P553T)-expressing primary murine hippocampal neurons showed decreased spine density, concomitant with reduced NMDA-evoked currents and impaired NMDAR-dependent insertion of the AMPA receptor subunit GluA1 at stimulated synapses. Furthermore, the naturally occurring coagonist d-serine restored function to GluN2B(P553T)-containing NMDARs. l-Serine dietary supplementation of the patient was hence initiated, resulting in the increased abundance of d-serine in the plasma and brain. The patient has shown notable improvements in motor and cognitive performance and communication after 11 and 17 months of l-serine dietary supplementation. Our data suggest that l-serine supplementation might ameliorate GRIN2B-related severe encephalopathy and other neurological conditions caused by glutamatergic signaling deficiency.

13-HODE, 9-HODE and ALOX15 as potential players in Rett syndrome OxInflammation.

Mutations in the MECP2 gene are the main cause of Rett syndrome (RTT), a pervasive neurodevelopmental disorder, that shows also multisystem disturbances associated with a metabolic component. The aim of this study was to investigate whether an increased production of oxidized linoleic acid metabolites, specifically 9- and 13-hydroxyoctadecadienoic acids (HODEs), can contribute to the altered the redox and immune homeostasis, suggested to be involved in RTT. Serum levels of 9- and 13-HODEs were elevated in RTT and associated with the expression of arachidonate 15-Lipoxygenase (ALOX15) in peripheral blood mononuclear cells (PBMCs). Omega-3 polyunsaturated fatty acids supplementation has shown to lower HODEs levels in RTT. Statistically significant correlation was demonstrated between the increased plasma HODEs levels and the lipoprotein-associated phospholipase A2 (Lp-PLA2) activity. Collectively, these findings reinforce the concept of the key role played by lipid peroxidation in RTT, and the possible ability of omega-3 polyunsaturated fatty acids supplementation in improving the oxinflammation status in RTT.

Chronic treatment with the phytocannabinoid Cannabidivarin (CBDV) rescues behavioural alterations and brain atrophy in a mouse model of Rett syndrome.

Rett syndrome (RTT) is a rare neurodevelopmental disorder, characterized by severe behavioural and physiological symptoms. RTT is caused by mutations in the MECP2 gene in about 95% of cases and to date no cure is available. The endocannabinoid system modulates several physiological processes and behavioural responses that are impaired in RTT and its deregulation has been associated with neuropsychiatric disorders which have symptoms in common with RTT. The present study evaluated the potential therapeutic efficacy for RTT of cannabidivarin (CBDV), a non-psychotropic phytocannabinoid from Cannabis sativa that presents antagonistic properties on the G protein-coupled receptor 55 (GPR55), the most recently identified cannabinoid receptor. Present results demonstrate that systemic treatment with CBDV (2, 20, 100 mg/Kg ip for 14 days) rescues behavioural and brain alterations in MeCP2-308 male mice, a validated RTT model. The CBDV treatment restored the compromised general health status, the sociability and the brain weight in RTT mice. A partial restoration of motor coordination was also observed. Moreover, increased levels of GPR55 were found in RTT mouse hippocampus, suggesting this G protein-coupled receptor as new potential target for the treatment of this disorder. Present findings highlight for the first time for RTT the translational relevance of CBDV, an innovative therapeutic agent that is under active investigation in the clinical setting.

RNA sequencing and proteomics approaches reveal novel deficits in the cortex of Mecp2-deficient mice, a model for Rett syndrome.

BACKGROUND: Rett syndrome (RTT) is an X-linked neurodevelopmental disorder caused by mutations in the transcriptional regulator MeCP2. Much of our understanding of MeCP2 function is derived from transcriptomic studies with the general assumption that alterations in the transcriptome correlate with proteomic changes. Advances in mass spectrometry-based proteomics have facilitated recent interest in the examination of global protein expression to better understand the biology between transcriptional and translational regulation. METHODS: We therefore performed the first comprehensive transcriptome-proteome comparison in a RTT mouse model to elucidate RTT pathophysiology, identify potential therapeutic targets, and further our understanding of MeCP2 function. The whole cortex of wild-type and symptomatic RTT male littermates (n = 4 per genotype) were analyzed using RNA-sequencing and data-independent acquisition liquid chromatography tandem mass spectrometry. Ingenuity® Pathway Analysis was used to identify significantly affected pathways in the transcriptomic and proteomic data sets. RESULTS: Our results indicate these two "omics" data sets supplement one another. In addition to confirming previous works regarding mRNA expression in Mecp2-deficient animals, the current study identified hundreds of novel protein targets. Several selected protein targets were validated by Western blot analysis. These data indicate RNA metabolism, proteostasis, monoamine metabolism, and cholesterol synthesis are disrupted in the RTT proteome. Hits common to both data sets indicate disrupted cellular metabolism, calcium signaling, protein stability, DNA binding, and cytoskeletal cell structure. Finally, in addition to confirming disrupted pathways and identifying novel hits in neuronal structure and synaptic transmission, our data indicate aberrant myelination, inflammation, and vascular disruption. Intriguingly, there is no evidence of reactive gliosis, but instead, gene, protein, and pathway analysis suggest astrocytic maturation and morphological deficits. CONCLUSIONS: This comparative omics analysis supports previous works indicating widespread CNS dysfunction and may serve as a valuable resource for those interested in cellular dysfunction in RTT.

A codon-optimized Mecp2 transgene corrects breathing deficits and improves survival in a mouse model of Rett syndrome.

Rett syndrome (RTT) is a severe X-linked neurodevelopmental disorder that is primarily caused by mutations in the methyl CpG binding protein 2 gene (MECP2). RTT is the second most prevalent cause of intellectual disability in girls and there is currently no cure for the disease. The finding that the deficits caused by the loss of Mecp2 are reversible in the mouse has bolstered interest in gene therapy as a cure for RTT. In order to assess the feasibility of gene therapy in a RTT mouse model, and in keeping with translational goals, we investigated the efficacy of a self-complementary AAV9 vector expressing a codon-optimized version of Mecp2 (AAV9-MCO) delivered via a systemic approach in early symptomatic Mecp2-deficient (KO) mice. Our results show that AAV9-MCO administered at a dose of 2×1011 viral genome (vg)/mouse was able to significantly increase survival and weight gain, and delay the occurrence of behavioral deficits. Apneas, which are one of the core RTT breathing deficits, were significantly decreased to WT levels in Mecp2 KO mice after AAV9-MCO administration. Semi-quantitative analysis showed that AAV9-MCO administration in Mecp2 KO mice resulted in 10 to 20% Mecp2 immunopositive cells compared to WT animals, with the highest Mecp2 expression found in midbrain regions known to regulate cardio-respiratory functions. In addition, we also found a cell autonomous increase in tyrosine hydroxylase levels in the A1C1 and A2C2 catecholaminergic Mecp2+ neurons in treated Mecp2 KO mice, which may partly explain the beneficial effect of AAV9-MCO administration on apneas occurrence.

Cytokine Dysregulation in MECP2- and CDKL5-Related Rett Syndrome: Relationships with Aberrant Redox Homeostasis, Inflammation, and ω-3 PUFAs.

An involvement of the immune system has been suggested in Rett syndrome (RTT), a devastating neurodevelopmental disorder related to oxidative stress, and caused by a mutation in the methyl-CpG binding protein 2 gene (MECP2) or, more rarely, cyclin-dependent kinase-like 5 (CDKL5). To date, it is unclear whether both mutations may have an impact on the circulating cytokine patterns. In the present study, cytokines involved in the Th1-, Th2-, and T regulatory (T-reg) response, as well as chemokines, were investigated in MECP2- (MECP2-RTT) (n = 16) and CDKL5-Rett syndrome (CDKL5-RTT) (n = 8), before and after ω-3 polyunsaturated fatty acids (PUFAs) supplementation. A major cytokine dysregulation was evidenced in untreated RTT patients. In MECP2-RTT, a Th2-shifted balance was evidenced, whereas in CDKL5-RTT both Th1- and Th2-related cytokines (except for IL-4) were upregulated. In MECP2-RTT, decreased levels of IL-22 were observed, whereas increased IL-22 and T-reg cytokine levels were evidenced in CDKL5-RTT. Chemokines were unchanged. The cytokine dysregulation was proportional to clinical severity, inflammatory status, and redox imbalance. Omega-3 PUFAs partially counterbalanced cytokine changes, as well as aberrant redox homeostasis and the inflammatory status. RTT is associated with a subclinical immune dysregulation as the likely consequence of a defective inflammation regulatory signaling system.

Red blood cells in Rett syndrome: oxidative stress, morphological changes and altered membrane organization.

In this review, we summarize the current evidence on the erythrocyte as a previously unrecognized target cell in Rett syndrome, a rare (1:10 000 females) and devastating neurodevelopmental disorder caused by loss-of-function mutations in a single gene (i.e. MeCP2, CDKL5, or rarely FOXG1). In particular, we focus on morphological changes, membrane oxidative damage, altered membrane fatty acid profile, and aberrant skeletal organization in erythrocytes from patients with typical Rett syndrome and MeCP2 gene mutations. The beneficial effects of ω-3 polyunsaturated fatty acids (PUFAs) are also summarized for this condition to be considered as a 'model' condition for autism spectrum disorders.

Altered erythrocyte membrane fatty acid profile in typical Rett syndrome: effects of omega-3 polyunsaturated fatty acid supplementation.

This study mainly aims at examining the erythrocyte membrane fatty acid (FAs) profile in Rett syndrome (RTT), a genetically determined neurodevelopmental disease. Early reports suggest a beneficial effects of omega-3 polyunsaturated fatty acids (ω-3 PUFAs) on disease severity in RTT. A total of 24 RTT patients were assigned to ω-3 PUFAs-containing fish oil for 12 months in a randomized controlled study (average DHA and EPA doses of 72.9, and 117.1mg/kgb.w./day, respectively). A distinctly altered FAs profile was detectable in RTT, with deficient ω-6 PUFAs, increased saturated FAs and reduced trans 20:4 FAs. FAs changes were found to be related to redox imbalance, subclinical inflammation, and decreased bone density. Supplementation with ω-3 PUFAs led to improved ω-6/ω-3 ratio and serum plasma lipid profile, decreased PUFAs peroxidation end-products, normalization of biochemical markers of inflammation, and reduction of bone hypodensity as compared to the untreated RTT group. Our data indicate that a significant FAs abnormality is detectable in the RTT erythrocyte membranes and is partially rescued by ω-3 PUFAs.

Acetyl-L-carnitine improves behavior and dendritic morphology in a mouse model of Rett syndrome.

Rett syndrome (RTT) is a devastating neurodevelopmental disorder affecting 1 in 10,000 girls. Approximately 90% of cases are caused by spontaneous mutations in the X-linked gene encoding methyl-CpG-binding protein 2 (MeCP2). Girls with RTT suffer from severe motor, respiratory, cognitive and social abnormalities attributed to early deficits in synaptic connectivity which manifest in the adult as a myriad of physiological and anatomical abnormalities including, but not limited to, dimished dendritic complexity. Supplementation with acetyl-L-carnitine (ALC), an acetyl group donor, ameliorates motor and cognitive deficits in other disease models through a variety of mechanisms including altering patterns of histone acetylation resulting in changes in gene expression, and stimulating biosynthetic pathways such as acetylcholine. We hypothesized ALC treatment during critical periods in cortical development would promote normal synaptic maturation, and continuing treatment would improve behavioral deficits in the Mecp2(1lox) mouse model of RTT. In this study, wildtype and Mecp2(1lox) mutant mice received daily injections of ALC from birth until death (postnatal day 47). General health, motor, respiratory, and cognitive functions were assessed at several time points during symptom progression. ALC improved weight gain, grip strength, activity levels, prevented metabolic abnormalities and modestly improved cognitive function in Mecp2 null mice early in the course of treatment, but did not significantly improve motor or cognitive functions assessed later in life. ALC treatment from birth was associated with an almost complete rescue of hippocampal dendritic morphology abnormalities with no discernable side effects in the mutant mice. Therefore, ALC appears to be a promising therapeutic approach to treating early RTT symptoms and may be useful in combination with other therapies.

White matter impairment in Rett syndrome: diffusion tensor imaging study with clinical correlations.

BACKGROUND AND PURPOSE: RTT, caused by mutations in the methyl CPG binding protein 2 (MeCP2) gene, is a disorder of neuronal maturation and connections. Our aim was to prospectively examine FA by DTI and correlate this with certain clinical features in patients with RTT. MATERIALS AND METHODS: Thirty-two patients with RTT underwent neurologic assessments and DTI. Thirty-seven age-matched healthy female control subjects were studied for comparison. With use of a 1.5T MR imaging unit, DTI data were acquired, and FA was evaluated to investigate multiple regional tract-specific abnormalities in patients with RTT. RESULTS: In RTT, significant reductions in FA were noted in the genu and splenium of the corpus callosum and external capsule, with regions of significant reductions in the cingulate, internal capsule, posterior thalamic radiation, and frontal white matter. In contrast, FA of visual pathways was similar to control subjects. FA in the superior longitudinal fasciculus, which is associated with speech, was equal to control subjects in patients with preserved speech (phrases and sentences) (P = .542), whereas FA was reduced in those patients who were nonverbal or speaking only single words (P < .001). No correlations between FA values for tracts and clinical features such as seizures, gross or fine motor skills, and head circumference were identified. CONCLUSIONS: DTI, a noninvasive technique to assess white matter tract pathologic features, may add specificity to the assessment of RTT clinical severity that is presently based on the classification of MeCP2 gene mutation and X-inactivation.

Brain metabolism in Rett syndrome: age, clinical, and genotype correlations.

OBJECTIVE: Brain metabolism, as studied by magnetic resonance spectroscopy (MRS), has been previously shown to be abnormal in Rett syndrome (RTT). This study reports the relation of MRS findings to age, disease severity, and genotype. METHODS: Forty RTT girls (1-14 years old) and 12 age-matched control subjects were examined. Single-voxel proton MRS of left frontal white matter was performed. RESULTS: NAA/Cr ratios decreased and myoinositol/Cr ratios increased with age in RTT patients (both p < 0.03), whereas these ratios were stable in control. The mean glutamate and glutamine/Cr ratio was 36% greater in RTT patients than in control (p = 0.043). The mean NAA/Cr ratio was 12.6% lower in RTT patients with seizures compared with those without seizures (p = 0.017). NAA/Cr ratios decreased with increasing clinical severity score (p = 0.031). Compared with patients with T158X, R255X, and R294X mutations, and C-terminal deletions, patients with the R168X mutation tended to have the greatest severity score (0.01 < or = p < or = 0.11) and the lowest NAA/Cr ratio (0.029 < or = p < 0.14). INTERPRETATION: Decreasing NAA/Cr and increasing myoinositol/Cr with age are suggestive of progressive axonal damage and astrocytosis in RTT, respectively, whereas increased glutamate and glutamine/Cr ratio may be secondary to increasing glutamate/glutamine cycling at the synaptic level. The relations between NAA/Cr, presence or absence of seizures, and disease severity suggest that MRS provides a noninvasive measure of cerebral involvement in RTT.

Neurochemical changes in a mouse model of Rett syndrome: changes over time and in response to perinatal choline nutritional supplementation.

Rett syndrome (RTT), the second leading cause of mental retardation in girls, is caused by mutations in the X-linked gene for methyl-CpG-binding protein 2 (MeCP2), a transcriptional repressor. In addition to well-documented neuroanatomical and behavioral deficits, RTT is characterized by reduced markers of cholinergic activity and general neuronal health. Previously, we have shown that early postnatal choline (Cho) supplementation improves behavioral and neuroanatomical symptoms in a mouse model of RTT (Mecp2(1lox) mice). In this study, we use NMR spectroscopy to quantify the relative amounts of Cho, Glutamate (Glu), Glutamine (Gln), and N-acetyl aspartate (NAA) in the brains of wild type and mutant mice at 21, 35, and 42 days of age and in mice receiving postnatal Cho supplementation. We find that the mutant mice have reduced levels of Cho, Glu, and NAA, but elevated Gln levels, compared with their wild type littermates. These differences emerge at different developmental ages. Cho supplementation increases NAA levels, a marker of neuronal integrity, but has no effect on Cho, Glu, or Gln. These data suggest that postnatal nutritional supplementation may improve neuronal function and could serve as a therapeutic agent for human RTT patients.

Effects of postnatal dietary choline supplementation on motor regional brain volume and growth factor expression in a mouse model of Rett syndrome.

Nutritional status during pregnancy and lactation can influence behavioral and anatomical characteristics of several neurological disorders in the offspring, including Rett syndrome (RTT). RTT is associated with mutations in the X-linked gene encoding methyl-CpG binding protein 2 (MeCp2), a transcriptional repressor that binds methylated DNA. In Mecp2(1lox) mice, a model of RTT, enhancing maternal nutrition through choline supplementation attenuates motor coordination deficits in the mutant offspring. Here, we examine alterations in brain volume and growth factor expression in the cerebellum and striatum, motor regions that may contribute to the improved behavioral performance seen with choline supplementation. Mecp2(1lox) dams were given choline in drinking water, and pups nursed from birth to weaning. Brains of male offspring were collected at postnatal day 42 for volumetric and growth factor expression analyses. Compared to wild-type mice, Mecp2(1lox) null mice had decreased whole brain, cerebellar and striatal volume. Choline supplementation had no effect on brain volume. Nerve growth factor and insulin-like growth factor-1 expression was similar between wild-type and Mecp2(1lox) mice while brain derived neurotrophic factor was reduced in Mecp2(1lox) mice. Choline supplementation increased striatal nerve growth factor expression in wild-type and Mecp2(1lox) mice, suggesting that neuronal proliferation and survival may contribute to improved motor performance in this model of RTT.

Longitudinal brain MRI study in a mouse model of Rett Syndrome and the effects of choline.

Rett Syndrome (RTT), the second most common cause of mental retardation in girls, is associated with mutations of an X-linked gene encoding the transcriptional repressor protein MeCP2. Mecp2(1lox) mutant mice express no functional MeCP2 protein and exhibit behavioral abnormalities similar to those seen in RTT patients. Here we monitor the development of both whole brain and regional volumes between 21 and 42 days of age in this model of RTT using MRI. We see decreases in whole brain volumes in both male and female mutant mice. Cerebellar and ventricular volumes are also decreased in RTT males. Previous work has suggested that perinatal choline supplementation alleviates some of the behavioral deficits in both male and female Mecp2(1lox) mutant mice. Here we show that perinatal choline supplementation also positively affects whole brain volume in heterozygous females, and cerebellar volume in male RTT mice.

General and oral characteristics in Rett syndrome.

Rett syndrome (RS) is a neurodegenerative disorder characterized by developmental arrest of parts of the brain. It is an X chromosome-linked condition which affects females almost exclusively. Recent reports have been generated concerning the multidisciplinary management of individuals exhibiting Rett syndrome. The aim of the present report was to provide an update on the oral manifestations of the disorder. We evaluated the general and oral characteristics of RS in 13 female patients. The most frequent manifestations were stereotyped hand movements and bruxism. The treatment we carried out included the use of biteplanes and acupuncture.

Substance P immunoreactivity in Rett syndrome.

Severe autonomic dysfunction occurs in Rett syndrome (RS). Substance P, a tachykinin peptide that localizes to several brain regions, including the autonomic nervous system, is reduced in the cerebrospinal fluid of patients with RS. The anatomic localization and intensity of substance P immunoreactivity and glial fibrillary acidic protein-positive astrocytes in the brains of 14 patients with RS were compared with those in the brains of 10 age-matched normal patients. Substance P immunoreactivity expression was significantly decreased in RS tissue compared with control tissue in the following regions: dorsal horns, intermediolateral column of the spinal cord, spinal trigeminal tract, solitary tract and nucleus, parvocellular and pontine reticular nuclei, and locus ceruleus. A less significant decrease of substance P immunoreactivity occurred in the substantia nigra, central gray of the midbrain, frontal cortex, caudate, putamen, globus pallidus, and thalamus. Antiglial fibrillary acidic protein-positive astrocytes were increased in the areas in which substance P immunoreactivity was decreased and in other brain regions. Because many of the brain regions with the greatest decrease in substance P immunoreactivity are involved in the control of the autonomic nervous system, especially the solitary tracts and reticular formation, reduced substance P may contribute to the autonomic dysfunction in RS.

Membrane cerebral lipids in Rett syndrome.

The lipid membrane composition of cerebral tissue from 5 patients with classic Rett syndrome, ages 12-30 years, and from 14 age-matched controls was studied. The results demonstrated a selective loss of myelin-associated lipids and an enrichment of gangliosides in temporal white matter. The ganglioside pattern revealed an increase of astroglial cell-associated gangliosides and reduced proportions of gangliosides GD1a and GT1b. This latter finding may be crucial in synaptic function. The fatty acid compositions of ethanolamine phosphoglyceride, choline phosphoglyceride, and galactosylceramide were normal.