Faculty Bibliography

Familial dysautonomia (FD) is a rare inherited neurodegenerative disorder. The most common mutation is a c.2204+6T>C transition in the 5' splice site (5'ss) of IKBKAP intron 20, which causes a tissue-specific skipping of exon 20, resulting in lower synthesis of IKAP/hELP1 protein. To better understand the specificity of neuron loss in FD, we modeled the molecular mechanisms of IKBKAP mRNA splicing by studying human olfactory ecto-mesenchymal stem cells (hOE-MSCs) derived from FD patient nasal biopsies. We explored how the modulation of IKBKAP mRNA alternative splicing impacts the transcriptome at the genome-wide level. We found that the FD transcriptional signature was highly associated with biological functions related to the development of the nervous system. In addition, we identified target genes of kinetin, a plant cytokinin that corrects IKBKAP mRNA splicing and increases the expression of IKAP/hELP1. We identified this compound as a putative regulator of splicing factors and added new evidence for a sequence-specific correction of splicing. In conclusion, hOE-MSCs isolated from FD patients represent a promising avenue for modeling the altered genetic expression of FD, demonstrating a methodology that can be applied to a host of other genetic disorders to test the therapeutic potential of candidate molecules. Hum Mutat 33:530-540, 2012. (c) 2011 Wiley Periodicals, Inc.

Familial dysautonomia (FD) is caused by an intronic splice mutation in the IKBKAP gene that leads to partial skipping of exon 20 and tissue-specific reduction in I-kappa-B kinase complex-associated protein/elongation protein 1 (IKAP/ELP-1) expression. Kinetin (6-furfurylaminopurine) has been shown to improve splicing and increase WT IKBKAP mRNA and IKAP protein expression in FD cell lines and carriers. To determine whether oral kinetin treatment could alter mRNA splicing in FD subjects and was tolerable, we administered kinetin to eight FD individuals homozygous for the splice mutation. Subjects received 23.5 mg/Kg/d for 28 d. An increase in WT IKBKAP mRNA expression in leukocytes was noted after 8 d in six of eight individuals; after 28 d, the mean increase compared with baseline was significant (p = 0.002). We have demonstrated that kinetin is tolerable in this medically fragile population. Not only did kinetin produce the desired effect on splicing in FD patients but also that effect seems to improve with time despite lack of dose change. This is the first report of a drug that produces in vivo mRNA splicing changes in individuals with FD and supports future long-term trials to determine whether kinetin will prove therapeutic in FD patients. ABBREVIATIONS::

The Riley-Day syndrome is the most common of the hereditary sensory and autonomic neuropathies (Type III). Among the well-recognized clinical features are reduced pain and temperature sensation, absent deep tendon reflexes and a progressively ataxic gait. To explain the latter we tested the hypothesis that muscle spindles, or their afferents, are absent in hereditary sensory and autonomic neuropathy III by attempting to record from muscle spindle afferents from a nerve supplying the leg in 10 patients. For comparison we also recorded muscle spindles from 15 healthy subjects and from two patients with hereditary sensory and autonomic neuropathy IV, who have profound sensory disturbances but no ataxia. Tungsten microelectrodes were inserted percutaneously into fascicles of the common peroneal nerve at the fibular head. Intraneural stimulation within muscle fascicles evoked twitches at normal stimulus currents (10-30 microA), and deep pain (which often referred) at high intensities (1 mA). Microneurographic recordings from muscle fascicles revealed a complete absence of spontaneously active muscle spindles in patients with hereditary sensory and autonomic neuropathy III; moreover, responses to passive muscle stretch could not be observed. Conversely, muscle spindles appeared normal in patients with hereditary sensory and autonomic neuropathy IV, with mean firing rates of spontaneously active endings being similar to those recorded from healthy controls. Intraneural stimulation within cutaneous fascicles evoked paraesthesiae in the fascicular innervation territory at normal stimulus intensities, but cutaneous pain was never reported during high-intensity stimulation in any of the patients. Microneurographic recordings from cutaneous fascicles revealed the presence of normal large-diameter cutaneous mechanoreceptors in hereditary sensory and autonomic neuropathy III. Our results suggest that the complete absence of functional muscle spindles in these patients explains their loss of deep tendon reflexes. Moreover, we suggest that their ataxic gait is sensory in origin, due to the loss of functional muscle spindles and hence a compromised sensorimotor control of locomotion

Familial dysautonomia (FD) is an autosomal recessive disorder characterized by autonomic and sensory neuropathy. Owing to pervasive dysfunction, the disease has protean clinical manifestations, affecting the ocular, gastrointestinal, pulmonary, orthopedic, vasomotor, and neurologic systems. The gastrointestinal perturbations, including dysphagia, gastroesophageal dysmotility, gastroesophageal reflux, and vomiting crises, are among the earliest signs. Here, we present the first 3 instances of gastric ulcers in patients with FD and discuss their common presenting features and the special management that was required

OBJECTIVE: Panayiotopoulos syndrome is a benign idiopathic childhood epilepsy characterized by altered autonomic activity at seizure onset. METHODS: Three siblings with Panayiotopoulos syndrome underwent 24-hour EEG recording and head-up tilt testing with continuous blood pressure and RR interval monitoring. Plasma catecholamines and vasopressin were measured while supine, upright, and during a typical seizure. RESULTS: Patient 1, a 12-year-old girl, had a history of involuntary lacrimation, abdominal pain, and recurrent episodes of loss of muscle tone and unresponsiveness followed by somnolence. Her EEG revealed bilateral frontotemporal spikes. Patient 2, a 10-year-old boy, had episodic headaches with pinpoint pupils, skin flushing of the face, trunk, and extremities, purple discoloration of hands and feet, diaphoresis, nausea, and vomiting. Tilt testing triggered a typical seizure after 9minutes; there was a small increase in blood pressure (+5/4mm Hg, systolic/diastolic) and pronounced increases in heart rate (+59bpm) and norepinephrine (+242pg/mL), epinephrine (+175pg/mL), and vasopressin (+22.1pg/mL) plasma concentrations. Serum glucose was elevated (206mg/dL). His EEG revealed right temporal and parietal spikes. Patient 3, an 8-year-old boy, had a history of restless legs at night, enuresis, night terrors, visual hallucinations, cyclic abdominal pain, and nausea. His EEG showed bitemporal spikes. CONCLUSION: Hypertension, tachycardia, and the release of vasopressin suggest activation of the central autonomic network during seizures in familial Panayiotopoulos syndrome. These autonomic and neuroendocrine features may be useful in the diagnosis and may have therapeutic implications

As a screening tool to identify symptoms of autonomic dysfunction, the Pediatric Autonomic Symptoms Scale was administered to parents of children with familial dysautonomia, autism spectrum disorders, and age-matched controls. The total scores for the presence of symptoms were compared among the 3 groups for each section and overall. The Pediatric Autonomic Symptoms Scale distinguished controls from children with familial dysautonomia and autism spectrum disorders with scores from each section and overall scores. Familial dysautonomia children scored significantly higher in visceral symptoms, while children with autism spectrum disorders scored significantly higher in psychosocial symptoms. In familial dysautonomia, the concordance for the presence of symptoms within sections and overall scores ranged from 71% to 100%. The concordance for absence of autonomic dysfunction symptoms in controls ranged from 75% to 87.5%. The Pediatric Autonomic Symptoms Scale is comprehensive and can profile autonomic dysfunction in the 2 neurodevelopmental disorders. Its usefulness in other pediatric disorders remains to be studied.

An increased incidence of neoplasia was recently reported in patients with familial dysautonomia. This suggests that, in addition to its role in neuronal development, the IKBKAP gene may also influence DNA repair. Here we report the case of a 28-year-old male with familial dysautonomia who was found to have neoplastic lesions detected post mortem as incidental findings. This case indicates that the prevalence of tumorgenesis within this population may be underestimated.

Background: Patients with familial dysautonomia (FD) fail to increase respiratory drive in response to low oxygen and high CO₂ levels. Many hypoventilate and have frequent apneic events during sleep, a time associated with an increased incidence of sudden death. To assess the need for non-invasive ventilation, patients with FD routinely undergo sleep studies with end-tidal CO₂ monitoring. Because most have severe lung disease, it is not known, however, whether end-tidal CO₂ levels accurately reflect arterial blood CO₂ levels. Methods: We studied 88 patients with FD (mean age 25 +/- 1, 45; females:43 males). We measured the partial pressure of CO₂ in blood obtained from the radial artery at the wrist (ABL80 FLEX, Radiometer, Denmark). End-tidal CO₂ was continuously sampled from a nasal canula (infrared analysis 5200 Ohmeda, USA). The average CO₂ value obtained over 10 full tidal breaths was used. All measurements were obtained during relaxed spontaneous breathing in the supine position. The relationship between end-tidal and arterial CO₂ measurements was examined using Pearson correlations. Results: All patients had a history of at least one aspiration pneumonia. The average partial pressure of oxygen in arterial blood was 87 +/- 2 mmHg. Thirty-one patients (36%) had arterial oxygen levels B80 mmHg. The average partial pressure of CO₂ was 43 +/- 0.4 mmHg (range 34-57 mmHg). Thirty-four patients (39%) had hypercapnia with CO₂ in arterial blood >=45 mmHg. Measurements of end-tidal CO₂ correlated tightly with CO₂ measured in arterial blood (y = 0.88x + 2.23, R² = 0.50, p<0.001). Conclusions: Our results show that in patients with FD, despite severe lung disease, the partial pressure of CO₂ measured in expired air (i.e. end tidal CO₂) accurately reflects the partial pressure ofCO₂ in arterial blood. Monitoring end tidal CO₂ is critically important to determine the potential role of apnea/hypoventilation in sudden death during sleep