A Rare Cause of Sleep-Disordered Breathing: ROHHAD Syndrome

Whole genome sequencing in ROHHAD trios proved inconclusive: what's beyond?

Rapid-onset Obesity with Hypothalamic dysfunction, Hypoventilation and Autonomic Dysregulation (ROHHAD) is a rare, life-threatening, pediatric disorder of unknown etiology, whose diagnosis is made difficult by poor knowledge of clinical manifestation, and lack of any confirmatory tests. Children with ROHHAD usually present with rapid onset weight gain which may be followed, over months or years, by hypothalamic dysfunction, hypoventilation, autonomic dysfunction, including impaired bowel motility, and tumors of neural crest origin. Despite the lack of evidence of inheritance in ROHHAD, several studies have been conducted in recent years that have explored possible genetic origins, with unsuccessful results. In order to broaden the search for possible genetic risk factors, an attempt was made to analyse the non-coding variants in two trios (proband with parents), recruited in the Gaslini Children's Hospital in Genoa (Italy). Both patients were females, with a typical history of ROHHAD. Gene variants (single nucleotide variants, short insertions/deletions, splice variants or in tandem expansion of homopolymeric tracts) or altered genomic regions (copy number variations or structural variants) shared between the two probands were searched. Currently, we have not found any potentially pathogenic changes, consistent with the ROHHAD clinical phenotype, and involving genes, regions or pathways shared between the two trios. To definitively rule out the genetic etiology, third-generation sequencing technologies (e.g., long-reads sequencing, optical mapping) should be applied, as well as other pathways, including those associated with immunological and autoimmune disorders, should be explored, making use not only of genomics but also of different -omic datasets.

Analysis and comparisons of gene expression changes in patient- derived neurons from ROHHAD, CCHS, and PWS

Background

Rapid-onset obesity with hypothalamic dysfunction, hypoventilation, and autonomic dysregulation (ROHHAD) syndrome is an ultra-rare neurocristopathy with no known genetic or environmental etiology. Rapid-onset obesity over a 3-12 month period with onset between ages 1.5-7 years of age is followed by an unfolding constellation of symptoms including severe hypoventilation that can lead to cardiorespiratory arrest in previously healthy children if not identified early and intervention provided. Congenital Central Hypoventilation syndrome (CCHS) and Prader-Willi syndrome (PWS) have overlapping clinical features with ROHHAD and known genetic etiologies. Here we compare patient neurons from three pediatric syndromes (ROHHAD, CCHS, and PWS) and neurotypical control subjects to identify molecular overlap that may explain the clinical similarities.

Methods

Dental pulp stem cells (DPSC) from neurotypical control, ROHHAD, and CCHS subjects were differentiated into neuronal cultures for RNA sequencing (RNAseq). Differential expression analysis identified transcripts variably regulated in ROHHAD and CCHS vs. neurotypical control neurons. In addition, we used previously published PWS transcript data to compare both groups to PWS patient-derived DPSC neurons. Enrichment analysis was performed on RNAseq data and downstream protein expression analysis was performed using immunoblotting.

Results

We identified three transcripts differentially regulated in all three syndromes vs. neurotypical control subjects. Gene ontology analysis on the ROHHAD dataset revealed enrichments in several molecular pathways that may contribute to disease pathology. Importantly, we found 58 transcripts differentially expressed in both ROHHAD and CCHS patient neurons vs. control neurons. Finally, we validated transcript level changes in expression of ADORA2A, a gene encoding for an adenosine receptor, at the protein level in CCHS neurons and found variable, although significant, changes in ROHHAD neurons.

Conclusions

The molecular overlap between CCHS and ROHHAD neurons suggests that the clinical phenotypes in these syndromes likely arise from or affect similar transcriptional pathways. Further, gene ontology analysis identified enrichments in ATPase transmembrane transporters, acetylglucosaminyltransferases, and phagocytic vesicle membrane proteins that may contribute to the ROHHAD phenotype. Finally, our data imply that the rapid-onset obesity seen in both ROHHAD and PWS likely arise from different molecular mechanisms. The data presented here describes important preliminary findings that warrant further validation.

Case Report: Considerations of nocturnal ventilator support in ROHHAD syndrome in chronic care of childhood central hypoventilation with hypothalamus dysfunction

Rapid-onset obesity with hypothalamic dysfunction, hypoventilation, and autonomic dysregulation (ROHHAD) is a rare life-threatening disorder that can occur during childhood. All children with ROHHAD develop alveolar hypoventilation during wakefulness and sleep. The key treatment for these patients is the optimization of oxygenation and ventilation. Here, we report the case of a 5-year-old girl with suspected ROHHAD, with rapid weight gain, breathing cessation, decreased height, hypoventilation, central hypothyroidism, hyperprolactinemia, and absolute deficiency of growth hormone, and negative PHOX2B sequencing results. The presentation met the diagnostic criteria for ROHHAD syndrome. During the 5-year follow-up, she presented with progressive deterioration of the function of the hypothalamus and respiratory center, hypoxemia (PO₂ < 60 mmHg), and hypercapnia [transcutaneous carbon dioxide (TcPCO₂) > 70 mmHg] during the first two cycles of N3 sleep with a poor response to ventilatory support. Early diagnosis and application of non-invasive positive pressure ventilation during sleep can improve the quality of life and outcomes of patients with ROHHAD, and polysomnography and TcPCO₂ should be repeated every 3-6 months to follow the progress and regulate ventilator support. Multidisciplinary care is crucial for the successful management of these patients.

Adrenal ganglioneuroma: Prognostic factors (Review)

Ganglioneuroma, a rare neural crest-derived tumor, exhibits a benign profile in contrast to other neuroblastic tumors (neuroblastoma/ganglioneuroblastoma). Ganglioneuromas can be found anywhere autonomic ganglia are located, mostly abdominal/pelvic sites followed by the adrenal glands (one-third of cases), mediastinum/thorax and cervical area. Affecting especially children more than 10 years of age, Ganglioneuroma is either asymptomatic or may cause local compressive effects; rarely inducing nonspecific abdominal complains or arterial hypertension related to oversecretion of epinephrine/norepinephrine/dopamine. Despite a good prognosis, adrenalectomy is necessary in order to rule out a malignancy. Open procedure represents the standard therapeutic option; alternatively, centers with large laparoscopic pediatric experience and good stratification protocols have reported successful procedures. High uptake of I¹²³-MIBG is associated with a more severe outcome in cases with increased mitotic index. In neuroblastic tumors, neuron-specific enolase >33 ng/ml, age at diagnosis <49 months, and blood vessel invasion indicate a poor prognosis. Concurrent extra-adrenal/adrenal ganglioneuroma is associated with a more severe prognosis; post-surgical complications are more frequent in non-adrenal vs. adrenal ganglioneuroma. Exceptionally, immune-mediated paraneoplastic neurologic syndromes have been reported: anti-N-methyl-D-aspartate receptor encephalitis and opsoclonus-myoclonus-ataxia syndrome. ROHHAD syndrome is the underlying cause in 40-56% of cases of neuroendocrine tumors including ganglioneuroma; 70% of tumors are diagnosed within the first 24 months after hypothalamic obesity onset, associated with a severe prognosis due to hypoventilation, sleep apnea, and dysautonomia. Recently, the PKB/AKT/mTOR/S6 pathway was identified as a tumorigenic pathway in pediatric ganglioneuroma, not in neuroblastoma; mTOR inhibitors are a potential option for pre-operatory tumor shrinkage. Pediatric adrenal ganglioneuroma has a good prognosis if adequately treated; its recognition requires adrenalectomy. Further development of specific biomarkers is needed. In the present article, we aimed to introduce a review of the literature involving adrenal ganglioneuroma based on a practical, multidisciplinary perspective of prognostic factors.

[Fever for 2 months and disturbance of consciousness for 1 week in a preschool-aged girl]

Rapid-onset obesity with hypothalamic dysfunction, hypoventilation, and autonomic dysregulation syndrome (ROHHADS) is a rare multi-system disease, and delayed diagnosis and treatment may lead to catastrophic cardiopulmonary complications. As far as we know, no patient with ROHHADS has been reported in China, and this article reports a child with ROHHADS to improve the awareness of this disease among clinicians. A girl, aged 3 years, had the clinical manifestations of rapid weight gain, fever, disturbance of consciousness, and convulsion. The physical examination showed a body weight of 20 kg, somnolence, irregular breathing, and stiff neck. She had increased blood levels of prolactin and follicle-stimulating hormone and hyponatremia. The lumbar puncture showed an increased intracranial pressure. The brain MRI and magnetic resonance venography showed symmetrical lesions in the periventricular region and venous thrombosis in the right transverse sinus and the superior sagittal sinus. The sleep monitoring showed hypopnea. The girl was finally diagnosed with ROHHADS and intracranial venous thrombosis. She recovered after symptomatic treatment including decreasing intracranial pressure, anticoagulation, and respiratory support. The possibility of ROHHADS should be considered for patients with unexplained obesity, fever, and hypoventilation, with or without central nervous system symptoms. Early diagnosis and standardized follow-up can improve the prognosis of children with ROHHADS.