Gail Reiner

Mitochondrial and ion channel gene alterations in autism.

To evaluate the potential importance in autistic subjects of copy number variants (CNVs) that alter genes of relevance to bioenergetics, ionic metabolism, and synaptic function, we conducted a detailed microarray analysis of 69 autism probands and 35 parents, compared to 89 CEU HapMap controls. This revealed that the frequency CNVs of≥100kb and CNVs of≥10 Kb were markedly increased in probands over parents and in probands and parents over controls. Evaluation of CNVs≥1Mb by chromosomal FISH confirmed the molecular identity of a subset of the CNVs, some of which were associated with chromosomal rearrangements. In a number of the cases, CNVs were found to alter the copy number of genes that are important in mitochondrial oxidative phosphorylation (OXPHOS), ion and especially calcium transport, and synaptic structure. Hence, autism might result from alterations in multiple bioenergetic and metabolic genes required for mental function. This article is part of a Special Issue entitled: 17th European Bioenergetics Conference (EBEC 2012).

Primary Respiratory Chain Disease Causes Tissue-Specific Dysregulation of the Global Transcriptome and Nutrient-Sensing Signaling Network

Primary mitochondrial respiratory chain (RC) diseases are heterogeneous in etiology and manifestations but collectively impair cellular energy metabolism. Mechanism(s) by which RC dysfunction causes global cellular sequelae are poorly understood. To identify a common cellular response to RC disease, integrated gene, pathway, and systems biology analyses were performed in human primary RC disease skeletal muscle and fibroblast transcriptomes. Significant changes were evident in muscle across diverse RC complex and genetic etiologies that were consistent with prior reports in other primary RC disease models and involved dysregulation of genes involved in RNA processing, protein translation, transport, and degradation, and muscle structure. Global transcriptional and post-transcriptional dysregulation was also found to occur in a highly tissue-specific fashion. In particular, RC disease muscle had decreased transcription of cytosolic ribosomal proteins suggestive of reduced anabolic processes, increased transcription of mitochondrial ribosomal proteins, shorter 5′-UTRs that likely improve translational efficiency, and stabilization of 3′-UTRs containing AU-rich elements. RC disease fibroblasts showed a strikingly similar pattern of global transcriptome dysregulation in a reverse direction. In parallel with these transcriptional effects, RC disease dysregulated the integrated nutrient-sensing signaling network involving FOXO, PPAR, sirtuins, AMPK, and mTORC1, which collectively sense nutrient availability and regulate cellular growth. Altered activities of central nodes in the nutrient-sensing signaling network were validated by phosphokinase immunoblot analysis in RC inhibited cells. Remarkably, treating RC mutant fibroblasts with nicotinic acid to enhance sirtuin and PPAR activity also normalized mTORC1 and AMPK signaling, restored NADH/NAD+ redox balance, and improved cellular respiratory capacity. These data specifically highlight a common pathogenesis extending across different molecular and biochemical etiologies of individual RC disorders that involves global transcriptome modifications. We further identify the integrated nutrient-sensing signaling network as a common cellular response that mediates, and may be amenable to targeted therapies for, tissue-specific sequelae of primary mitochondrial RC disease.

Frequency and Complexity of De Novo Structural Mutation in Autism

Genetic studies of autism spectrum disorder (ASD) have established that de novo duplications and deletions contribute to risk. However, ascertainment of structural variants (SVs) has been restricted by the coarse resolution of current approaches. By applying a custom pipeline for SV discovery, genotyping, and de novo assembly to genome sequencing of 235 subjects (71 affected individuals, 26 healthy siblings, and their parents), we compiled an atlas of 29,719 SV loci (5,213/genome), comprising 11 different classes. We found a high diversity of de novo mutations, the majority of which were undetectable by previous methods. In addition, we observed complex mutation clusters where combinations of de novo SVs, nucleotide substitutions, and indels occurred as a single event. We estimate a high rate of structural mutation in humans (20%) and propose that genetic risk for ASD is attributable to an elevated frequency of gene-disrupting de novo SVs, but not an elevated rate of genome rearrangement.

Low‐dose suramin in autism spectrum disorder: a small, phase I/II, randomized clinical trial

No drug is yet approved to treat the core symptoms of autism spectrum disorder (ASD). Low‐dose suramin was effective in the maternal immune activation and Fragile X mouse models of ASD. The Suramin Autism Treatment‐1 (SAT‐1) trial was a double‐blind, placebo‐controlled, translational pilot study to examine the safety and activity of low‐dose suramin in children with ASD.

A clinical trial of safety and tolerability for the selective dopamine D1 receptor antagonist ecopipam in patients with Lesch-Nyhan disease

Lesch-Nyhan disease (LND) is an inherited metabolic disorder characterized by the overproduction of uric acid and distinct behavioral, cognitive, and motor abnormalities. The most challenging clinical problem is self-injurious behavior (SIB), which includes self-biting, self-hitting, self-abrasion, and other features. Currently, these behaviors are managed by behavioral extinction, sedatives, physical restraints, and removal of teeth. More effective treatments are needed. Pre-clinical studies have led to the hypothesis that D1-dopamine receptor antagonists may provide useful treatments for SIB in LND. Ecopipam is one such selective D1-dopamine receptor antagonist. This report summarizes results of a dose-escalation study of the safety and tolerability of ecopipam in 5 subjects with LND. The results suggest that ecopipam is well tolerated, with sedation being the most common dose-limiting event. Several exploratory measures also suggest ecopipam might reduce SIB in this population. These results support the hypothesis that D1-dopamine receptor antagonists may be useful for suppressing SIB in LND, and encourage further studies of efficacy.

Assessing Bioenergetic Compromise in Autism Spectrum Disorder With 31P Magnetic Resonance Spectroscopy Preliminary Report

We sought to examine, via Phosphorus-31 magnetic resonance spectroscopy (31P-MRS) in a case-control design, whether bioenergetic deficits in autism spectrum disorders extend to the brain and muscle. Six cases with autism spectrum disorder with suspected mitochondrial dysfunction (age 6-18 years) and 6 age/sex-matched controls underwent 31P magnetic resonance spectroscopy. The outcomes of focus were muscle resting phosphocreatine and intracellular pH as well as postexercise phosphocreatine recovery time constant and frontal brain phosphocreatine. Intracellular muscle pH was lower in each autism spectrum disorder case than their matched control (6/6, P = .03; P = .0048, paired t test). Muscle phosphocreatine (5/6), brain phosphocreatine (3/4), and muscle phosphocreatine recovery time constant (3/3) trends were in the predicted direction (not all participants completed each). This study introduces 31P magnetic resonance spectroscopy as a noninvasive tool for assessment of mitochondrial function in autism spectrum disorder enabling bioenergetic assessment in brain and provides preliminary evidence suggesting that bioenergetic defects in cases with autism spectrum disorder are present in muscle and may extend to brain.

Assessing Bioenergetic Compromise in Autism Spectrum Disorder With 31P Magnetic Resonance Spectroscopy

We sought to examine, via Phosphorus-31 magnetic resonance spectroscopy (31P-MRS) in a case-control design, whether bioenergetic deficits in autism spectrum disorders extend to the brain and muscle. Six cases with autism spectrum disorder with suspected mitochondrial dysfunction (age 6-18 years) and 6 age/sex-matched controls underwent 31P magnetic resonance spectroscopy. The outcomes of focus were muscle resting phosphocreatine and intracellular pH as well as postexercise phosphocreatine recovery time constant and frontal brain phosphocreatine. Intracellular muscle pH was lower in each autism spectrum disorder case than their matched control (6/6, P = .03; P = .0048, paired t test). Muscle phosphocreatine (5/6), brain phosphocreatine (3/4), and muscle phosphocreatine recovery time constant (3/3) trends were in the predicted direction (not all participants completed each). This study introduces 31P magnetic resonance spectroscopy as a noninvasive tool for assessment of mitochondrial function in autism spectrum disorder enabling bioenergetic assessment in brain and provides preliminary evidence suggesting that bioenergetic defects in cases with autism spectrum disorder are present in muscle and may extend to brain.

Paroxysmal motor disorders: expanding phenotypes lead to coalescing genotypes

Paroxysmal movement disorders encompass varied motor phenomena. Less recognized features and wide phenotypic and genotypic heterogeneity are impediments to straightforward molecular diagnosis. We describe a family with episodic ataxia type 1, initially mis‐characterized as paroxysmal dystonia to illustrate this diagnostic challenge. We summarize clinical features in affected individuals to highlight underappreciated aspects and provide comprehensive phenotypic description of the rare familial KCNA1 mutation. Delayed diagnosis in this family is emblematic of the broader challenge of diagnosing other paroxysmal motor disorders. We summarize genotypic and phenotypic overlap and provide a suggested diagnostic algorithm for approaching patients with these conditions.

Inborn error metabolic screening in nonsyndromic autism spectrum disorders.

(MOG, n=5), aquaporin-4 (AQP4, n=1), and voltage-gated potassium channels (n=3). Because the etiology of brainstem encephalitis is widely unknown, the results described by Hacohen et al. contribute important knowledge to immunological aspects of the disease in pediatric patients. Although the numbers of patients with antibodies were small in each group, they presented with typical clinical phenotypes. NMDAR antibodies were only found in the encephalitis group, and the association of these antibodies with psychiatric features, movement disorders, or seizures – which are the main symptoms characteristic for autoimmune encephalitis – fits with the typical presentation of NMDAR encephalitis. In contrast, MOG antibodies were seen exclusively in patients with white matter involvement such as clinical isolated syndrome or acute disseminated encephalomyelitis (ADEM). The low percentage of MOG antibodies in this ADEM group compared to a recent study prospectively investigating clinical and neuroradiological courses of ADEM patients, which identified MOG antibodies in 58% of the patients, might be explained by the overrepresentation of BBE patients. Compared to previous studies, Hacohen et al. observed different frequencies of antibody distributions, which could be explained by the characteristics and limitations of their current study. The cohort they investigated is a clinically heterogeneous population of pediatric brain stem encephalitis patients, which corresponds well to a ‘real life setting’ in a referral center. Nevertheless, the high frequency of GQ1b antibodies among patients with confirmed Bickerstaff’s brainstem encephalitis (43%) has to be, at least in part, attributed to a selection bias, because serum samples investigated here were initially collected for GQ1b antibody testing. As pointed out by the authors, further limitations such as testing a purely Japanese cohort and the lack of cerebrospinal fluid might yield skewed results. Group sizes of each antibody found by Hacohen et al. were small, so statistical analysis has limited value for any implications on treatment strategies. However, two patients with NMDAR antibodies and persisting severe learning difficulties suggest the need for a more aggressive immunotherapy in those patients. The patient with AQP4 antibodies described here parallels a recently identified case of brainstem syndrome presenting with AQP4 antibodies, which suggests the need for laboratory testing for AQP4 antibodies in patients with brainstem involvement. In sum, for pediatric patients with CNS inflammation involving the brainstem, one should be aware of possible contributions of antibodies to glial and neuronal antigens. By reasonably interpreting characteristic clinical symptoms, the identification of relevant antibodies at onset (in particular NMDAR, AQP4, and MOG antibodies) could influence treatment strategies towards a more or less intensive immunotherapy.