Transitional care and clinical management of adolescents, young adults, and suspected new adult patients with congenital central hypoventilation syndrome

Computer-aided diagnostic screen for Congenital Central Hypoventilation Syndrome with facial phenotype

BACKGROUND

Congenital Central Hypoventilation Syndrome (CCHS) has devastating consequences if not diagnosed promptly. Despite identification of the disease-defining gene PHOX2B and a facial phenotype, CCHS remains underdiagnosed. This study aimed to incorporate automated techniques on facial photos to screen for CCHS in a diverse pediatric cohort to improve early case identification and assess a facial phenotype-PHOX2B genotype relationship.

METHODS

Facial photos of children and young adults with CCHS were control-matched by age, sex, race/ethnicity. After validating landmarks, principal component analysis (PCA) was applied with logistic regression (LR) for feature attribution and machine learning models for subject classification and assessment by PHOX2B pathovariant.

RESULTS

Gradient-based feature attribution confirmed a subtle facial phenotype and models were successful in classifying CCHS: neural network performed best (median sensitivity 90% (IQR 84%, 95%)) on 179 clinical photos (versus LR and XGBoost, both 85% (IQR 75-76%, 90%)). Outcomes were comparable stratified by PHOX2B genotype and with the addition of publicly available CCHS photos (n = 104) using PCA and LR (sensitivity 83-89% (IQR 67-76%, 92-100%).

CONCLUSIONS

Utilizing facial features, findings suggest an automated, accessible classifier may be used to screen for CCHS in children with the phenotype and support providers to seek PHOX2B testing to improve the diagnostics.

IMPACT

Facial landmarking and principal component analysis on a diverse pediatric and young adult cohort with PHOX2B pathovariants delineated a distinct, subtle CCHS facial phenotype. Automated, low-cost machine learning models can detect a CCHS facial phenotype with a high sensitivity in screening to ultimately refer for disease-defining PHOX2B testing, potentially addressing gaps in disease underdiagnosis and allow for critical, timely intervention.

Multidisciplinary approach to congenital central hypoventilation syndrome during pregnancy: case report

Congenital central hypoventilation syndrome is a rare genetic disorder that affects control of breathing caused by variants in the paired-like homeobox 2B (PHOX2B) gene. During pregnancy, women with congenital central hypoventilation syndrome are at risk for hypoventilation and require frequent assessments of oxygenation and ventilation during wakefulness and sleep on their ventilator. This could potentially lead to adjustments in the ventilator settings or a change in the assisted ventilation modality. We report the case of a 31-year-old pregnant woman with congenital central hypoventilation syndrome and an implanted cardiac pacemaker who underwent prenatal genetic testing for congenital central hypoventilation syndrome and who delivered a healthy newborn by cesarean delivery. She received collaborative multidisciplinary care from a team that included specialists in obstetrics, maternal and fetal medicine, medical genetics, sleep and pulmonary medicine, cardiology, and anesthesiology. She used bilevel positive airway pressure therapy throughout pregnancy and after cesarean delivery without requiring adjustments in the bilevel positive airway pressure settings. Our case highlights the importance of multidisciplinary care in women with congenital central hypoventilation syndrome during pregnancy to optimize pregnancy and fetal outcomes.

Obstructive sleep apnea as a presentation of congenital central hypoventilation syndrome

Congenital central hypoventilation syndrome is a rare disorder due to a mutation in the PHOX2B gene, characterized by a failure in autonomic control of breathing with diminished or absent response to hypoxia and hypercapnia, which is most pronounced during sleep. Most patients present from birth with central apneas and hypoventilation, or later in the setting of a physiologic stress. Recent literature in mice with a Phox2b27Ala/+ mutation suggests a predisposition to obstructive apneas likely due to hypoglossal dysgenesis. We report on three patients with obstructive sleep apneas with absent or mild hypoventilation. Our cases propose that obstructive apneas can be the primary presentation in patients who subsequently develop the classic phenotype of congenital central hypoventilation syndrome and emphasize their close monitoring and surveillance.

CITATION

Kagan O, Zhang C, McElyea C, Keens TG, Davidson Ward SL, Perez IA. Obstructive sleep apnea as a presentation of congenital central hypoventilation syndrome. J Clin Sleep Med. 2023;19(9):1697-1700.

Congenital Central Hypoventilation Syndrome in Israel-Novel Findings from a New National Center

BACKGROUND

Congenital central hypoventilation syndrome (CCHS) is a rare autosomal-dominant disorder of the autonomic nervous system that results from mutations in the PHOX2B gene. A national CCHS center was founded in Israel in 2018. Unique new findings were observed.

METHODS

All 27 CCHS patients in Israel were contacted and followed. Novel findings were observed.

RESULTS

The prevalence of new CCHS cases was almost twice higher compared to other countries. The most common mutations in our cohort were polyalanine repeat mutations (PARM) 20/25, 20/26, 20/27 (combined = 85% of cases). Two patients showed unique recessive inheritance while their heterozygotes family members were asymptomatic. A right-sided cardio-neuromodulation was performed on an eight-year-old boy for recurrent asystoles by ablating the parasympathetic ganglionated plexi using radiofrequency (RF) energy. Over 36 months' follow-up with an implantable loop-recorder, no bradycardias/pauses events were observed. A cardiac pacemaker was avoided.

CONCLUSIONS

A significant benefit and new information arise from a nationwide expert CCHS center for both clinical and basic purposes. The incidence of CCHS in some populations may be increased. Asymptomatic NPARM mutations may be much more common in the general population, leading to an autosomal recessive presentation of CCHS. RF cardio-neuromodulation offers a novel approach to children avoiding the need for permanent pacemaker implantation.

Congenital central hypoventilation syndrome without hypoventilation: is it congenital central hypoventilation syndrome?

Congenital central hypoventilation syndrome (CCHS) is a rare condition caused by pathogenic variants of the PHOX2B gene. There have been case reports describing variable phenotypes and mutations of the PHOX2B gene, not commonly tested for, that may challenge the classic definition of CCHS. We report on 3 family members with a rare heterozygous deletion encompassing the entire PHOX2B gene with variable phenotypes, including sleep-disordered breathing and autonomic nervous system involvement, but an unexpected lack of alveolar hypoventilation, which is usually a defining feature of CCHS. Our cases highlight the dilemmas in making a diagnosis of CCHS and emphasize the need for expanded genetic testing, including for PHOX2B gene deletion. More patients with variable phenotypes of CCHS may be identified through comprehensive genetic testing and warrant surveillance as they are still at risk for high-risk complications of CCHS.

CITATION

Wo LL, Itani R, Keens TG, Marachelian A, Ji J, Perez IA. Congenital central hypoventilation syndrome without hypoventilation: is it congenital central hypoventilation syndrome? J Clin Sleep Med. 2023;19(6):1161-1164.

Congenital Central Hypoventilation Syndrome: Diagnosis and Long-Term Ventilatory Outcomes

Background

Congenital central hypoventilation syndrome (CCHS), a rare disease caused by variants in the paired-like homeobox 2B (PHOX2B) gene, affects regulation of respiration necessitating lifelong assisted ventilation (AV). Most patients require full-time AV during infancy and some patients may sustain adequate spontaneous ventilation during wakefulness and change AV modalities at a later age. The aims of this study were to assess the changes in duration and modalities of AV, long-term respiratory outcomes, and to correlate them with PHOX2B genotypes.

Methods

We conducted a retrospective study of patients with CCHS treated at our institution between January 1997 and May 2022. Results analyzed included: clinical presentation, PHOX2B genotype, modality and duration of AV at diagnosis and follow-up, survival, and transition to adult care.

Results

We identified 30 patients with CCHS-8 with PHOX2B nonpolyalanine repeat mutations (NPARMs), 21 with polyalanine repeat mutations (PARMs), and 1 with unknown PHOX2B genotype. The median age at presentation was 0.25 months (IQR 0.1-0.7 months). At diagnosis of CCHS, 24 (80%) patients required continuous AV and 28 (93%) received AV via tracheostomy. Twenty-six patients required sleep-only AV at a median age of 9 months (IQR 6-14 months). Nine patients requiring sleep-only AV underwent tracheostomy decannulation at a median age of 11.2 years (IQR 5.9-15.7 years) and used noninvasive positive pressure ventilation or diaphragm pacing. There was insufficient evidence to conclude that patients with PARMs and NPARMs differed by age at presentation (P = .39), tracheostomy (P = .06), and transition to sleep-only AV (P = .9). Six patients transitioned to adult care, 23 continued receiving pediatric care, and 1 patient died due to complications from Hirschsprung's disease.

Conclusion

Our study demonstrates prolonged survival and good long-term respiratory outcomes possibly related to the early diagnosis of CCHS, optimizing AV strategies, and multidisciplinary care. The increasing number of patients attaining adulthood highlights the necessity for multidisciplinary care for adults with CCHS.