Faculty Bibliography

Background: Reduced pain and temperature sensation with varying degrees of autonomic dysfunction are characteristic features of patients with hereditary sensory and autonomic neuropathies (HSAN). At least seven HSAN phenotypes have been described for which 14 gene mutations have been identified. In many patients presenting with congenital sensory and autonomic deficits, however, traditional genetic testing is unable to detect genetic mutations. Objective: To identify novel genetic causes of congenital impaired sensation to pain with autonomic dysfunction with whole exome sequencing and evaluate genotype-phenotype correlations. Methods: We enrolled 10 patients with impaired or absent sensation to pain and temperature sensation with onset at birth without a previously identified molecular diagnosis from a HSAN gene panel. We performed detailed phenotypic assessment including presentation, autonomic testing, and comprehensive neurological and ophthalmo-logical examinations. Whole exome sequencing was performed in all patients as well as in, at least, one family member. Results: In 9 of 10 (90%) patients with congenital impaired pain sensation, we identified variants predicted to be pathogenic in NGF (n = 2, siblings), SMPDL3A (n = 2, siblings), SCN11A (n = 1), SCN10A (n = 1), SCN9A (n = 1), LIFR (n = 1), and TECPR2 (n = 1). Only in one patient, whole exome sequencing was not useful to identify potential pathogenic variants. Autonomic deficits included anhidrosis (SCN9A, NGF), hypohidrosis (TECPR2), hyperhidrosis (SCN11A, SCN10A, TECPR2, LIFR), alacrima or hypolacrima (SMPDL3A, TECPR2, LIFR), neurogenic dysphagia (TECPR2, SMPDL3A, SCN11A), gastroesophageal reflux (SCN11A), vomiting episodes (LIFR), and central sleep apnea (TECPR2). The subject with LIFR had episodes of hypertension, tachycardia, severe hyperhidrosis and hypernatremia. Sensorineural hearing loss was present in TECPR2 and one of the subjects with SMPDL3A. Conclusions: We characterize and expand the genetic landscape of HSAN, and demonstrate the feasibility of genetic diagnosis with clinically whole exome sequencing in 90% of our cohort

Background: The arterial baroreflex buffers blood pressure to prevent it from rising or falling excessively. Afferent baroreflex failure occurs in patients with genetic or acquired lesions of the afferent (sensory) baroreceptor nerves relaying information to the brain or within the central connections of the medulla. Patients with afferent baroreflex failure have extremely volatile high and quite low pressures. Review of the literature reveals that acquired forms of afferent baroreflex failure have never been described in children or young adults. Aim: To define the cause, clinical spectrum, and treatment of acquired baroreflex failure in children and young adults. Methods: We prospectively studied consecutive pediatric and young adult patients (<30 years old) who were diagnosed with afferent baroreflex failure. Each patient underwent a detailed clinical history, neurological examination, autonomic testing, plasma catecholamine measurements, and ambulatory blood pressure monitoring. Results: We identified 6 patients (3 males and 3 females; age range: 11-28 years old). All presented with severe, labile hypotension with syncope and hypertension often accompanied by headache, and flushing. Office blood pressure ranged from a maximum of 198/138 to 143/90 mmHg and a minimum of 70/40 to 102/68 mmHg. Plasma norepinephrine levels failed to increase appropriately during head-up. On ambulatory monitoring, 24-h systolic blood pressure standard deviation was markedly exaggerated (from 17.5 to 20.8 mmHg). In all cases, patients had excessive pressor and tachycardic responses to cognitive arousal (mental-arithmetic). The underlying causes of the afferent baroreflex failure included surgery and radiotherapy of head or neck cancer (n = 4), posterior reversible leukoencephalopathy (n = 1), and Moebius syndrome (n = 1). Conclusions: Acquired afferent baroreflex failure should be considered in children and young adults with otherwise unexplained labile hypertension, particularly in those with a history of head or neck cancer

Introduction: Familial dysautonomia (FD) is a rare autosomal recessive disorder caused by a point mutation in the IKBKAP gene, resulting in reduction of the IkappaB Kinase-associated protein/Elongator protein 1 (IKAP/ELP1). ELP1 is a transcriptional regulator that targets downstream genes involved with cell migration, stability and survival. We hypothesized that ELP1-associated abnormalities may increase the incidence and prevalence of neoplasia and cancer in FD. Methods: Retrospective chart review of the New York University FD Patient International Registry, which contains standardized clinical information on patients with genetically confirmed FD since 1970. We identified cases with neoplasia or cancer, and reviewed their demographics, tumor type and age at diagnosis. Results: At the time of writing, of the 674 patients with FD reviewed, we identified 25 cases of neoplasia, which included 12 cases of cancer. The prevalence of neoplasia in the FD population was 3.7% and the prevalence of cancer was 1.8%. Average age at cancer diagnosis was 29 years, significantly younger than in the general population (66 years). Additionally, 16% of all neoplasia were tumors derived from neural crest cells. There was no association between growth hormone treatment and the prevalence of neoplasia or cancer. Conclusions: Patients with FD have higher rates of neoplasia and cancer than previously reported in the literature. Overall, the FD population develops cancer and tumors at a much younger atypical age than the general population. Our results suggest that ELP1 plays an important role in tumor genesis and may explain the high prevalence of neoplasia and cancer in patients with FD

Background: Allgrove syndrome (triple A syndrome) is a rare autosomal recessive disorder first described by endocrinologist Jeremy Allgrove in 1978 in two siblings with adrenal insufficiency, achalasia, and alacrima. Onset is usually within the first decade of life. Other features include adrenocorticotropic hormone (ACTH) unresponsiveness, and varying degrees of neurologic dysfunction. In 2002, mutations in the AAAS gene located on chromosome 12q13, which encodes for the nuclear pore protein ALADIN, were reported as the cause of the disease. The autonomic features of the disorder remain poorly understood with only ~ 100 cases in the literature, most of which were described before the availability of genetic testing. Methods: Case series of 2 patients with genetically confirmed Allgrove syndrome. Results: Case # 1: 9-year-old girl of East Indian descent presented with alacrima since birth. At age 6, she developed adrenal insufficiency manifesting as hyperpigmentation and fatigue. Genetic testing confirmed she was homozygous for the pathogenic variant c.1432C>T p.Arg478Ter. The patient had no achalasia and neurological exam was normal. Cardiovascular autonomic testing was normal. Case # 2: 39-year-old Hispanic woman presented with alacrima, achalasia, ACTH resistance, and sensorimotor polyneuropathy at the age of 13 years. Autonomic testing revealed adrenergic impairment with orthostatic hypotension together with cholinergic dysfunction and decreased heart rate variability. Genetic testing confirmed two heterozygous mutations: 1) Heterozygous Exon 6, R155P, base 464 CGT to CCT; 2) Heterozygous IVSC14 + 1G to A. Mutation 1 had not been previously reported. Conclusions: Allgrove syndrome is a rare pediatric-onset disorder with variable presentation. Neurological signs (autonomic dysfunction, hyperreflexia, dysarthria, ataxia, sensory impairment, weakness, cognitive deficits) and ACTH resistance may only manifest after many years or decades. As the number of genetically confirmed cases grows, there is a need to understand the autonomic phenotype, which should perhaps be considered the 4th A

Study Objectives: Sudden unexpected death during sleep (SUDS) is the most common cause of death in patients with familial dysautonomia, an autosomal recessive disease characterized by sensory and autonomic dysfunction. It remains unknown what causes SUDS in these patients and who is at highest risk. We tested the hypothesis that SUDS in FD is linked to sleep-disordered breathing. Methods: We retrospectively identified patients with familial dysautonomia who died suddenly and unexpectedly during sleep and had undergone polysomnography within the 18-month period prior to death. For each case, we sampled one age-matched surviving subject with familial dysautonomia that had also undergone polysomnography within the 18-month period prior to study. Data on polysomnography, EKG, ambulatory blood pressure monitoring, arterial blood gases, blood count, and metabolic panel were analyzed. Results: Thirty-two deceased cases and 31 surviving controls were included. Autopsy was available in 6 cases. Compared with controls, subjects with SUDS were more likely to be receiving treatment with fludrocortisone (odds ratio; 95% confidence interval) (OR 29.7; 4.1-213.4), have untreated obstructive sleep apnea (OR 17.4; 1.5-193) and plasma potassium levels < 4 mEq/L (OR 19.5; 2.36-161), but less likely to use non-invasive ventilation at night (OR 0.19; 0.06-0.61). Conclusions: Initiation of non-invasive ventilation when required, and discontinuation of fludrocortisone treatment may reduce the high incidence rate of SUDS in patients with familial dysautonomia. Our findings contribute to the understanding of the link between autonomic, cardiovascular, and respiratory risk factors in sudden unexpected death during sleep.

PURPOSE: To report the use of intranasal dexmedetomidine, an alpha2-adrenergic agonist for the acute treatment of refractory adrenergic crisis in patients with familial dysautonomia. METHODS: Case series. RESULTS: Three patients with genetically confirmed familial dysautonomia (case 1: 20-year-old male; case 2: 43-year-old male; case 3: 26-year-old female) received intranasal dexmedetomidine 2 mcg/kg, half of the dose in each nostril, for the acute treatment of adrenergic crisis. Within 8-17 min of administering the intranasal dose, the adrenergic crisis symptoms abated, and blood pressure and heart rate returned to pre-crises values. Adrenergic crises eventually resumed, and all three patients required hospitalization for investigation of the cause of the crises. CONCLUSIONS: Intranasal dexmedetomidine is a feasible and safe acute treatment for adrenergic crisis in patients with familial dysautonomia. Further controlled studies are required to confirm the safety and efficacy in this population.

Familial dysautonomia is an inherited autonomic disorder with afferent baroreflex failure. We questioned why despite low blood pressure standing, surprisingly few familial dysautonomia patients complain of symptomatic hypotension or have syncope. Using transcranial Doppler ultrasonography of the middle cerebral artery, we measured flow velocity (mean, peak systolic, and diastolic), area under the curve, pulsatility index, and height of the dictrotic notch in 25 patients with familial dysautonomia and 15 controls. In patients, changing from sitting to a standing position, decreased BP from 124 +/- 4/64 +/- 3 to 82 +/- 3/37 +/- 2 mmHg (p < 0.0001, for both). Despite low BP, all patients denied orthostatic symptoms. Middle cerebral artery velocity fell minimally, and the magnitude of the reductions were similar to those observed in healthy controls, in whom BP upright did not fall. While standing, patients had a greater fall in cerebrovascular resistance (p < 0.0001), an increase in pulsatility (p < 0.0001), and a deepening of the dicrotic notch (p = 0.0010), findings all consistent with low cerebrovascular resistance. No significant changes occurred in controls. Patients born with baroreflex deafferentation retain the ability to buffer wide fluctuations in BP and auto-regulate cerebral blood flow. This explains how they can tolerate extremely low BPs standing that would otherwise induce syncope.