Familial dysautonomia: frequent, prolonged and severe hypoxemia during wakefulness and sleep

Area of Science:

• Cardiology
• Pulmonology
• Genetics
• Pediatrics

Background:

• Familial Dysautonomia (FD) is a rare genetic disorder affecting the autonomic nervous system.
• Sudden unexplained death occurs in a significant percentage of FD subjects, highlighting the need to understand contributing factors.
• Cardiorespiratory dysregulation is suspected to play a role in the mortality associated with FD.

Purpose of the Study:

• To characterize cardiorespiratory dysregulation in children with Familial Dysautonomia (FD).
• To investigate potential links between cardiorespiratory abnormalities and sudden death risk in FD.
• To compare cardiorespiratory patterns during wakefulness and sleep between FD children and healthy controls.

Main Methods:

• Twenty-five children with IKBKAP mutation-confirmed FD and 25 age/gender-matched controls participated.
• Cardiorespiratory parameters were monitored at home using respiratory inductance plethysmography, ECG, and pulse oximetry during wakefulness and sleep.
• Breath-to-breath and beat-to-beat analyses were performed to characterize breathing, hemoglobin saturation, and heart rate.

Main Results:

• Children with FD exhibited significantly more frequent, prolonged, and severe episodes of hypoxemia compared to controls, both awake and asleep.
• Apnea was more prevalent in FD subjects than controls, particularly during sleep, though hypoxemia was the most common finding.
• Bradycardia was infrequent and rarely coincided with hypoxemia or apnea in FD patients.

Conclusions:

• Children with FD demonstrate significant cardiorespiratory dysregulation, including alveolar hypoventilation, during wakefulness and sleep.
• Recurrent hypoxemia, potentially with associated hypercarbia, is a key finding in FD.
• This cardiorespiratory instability may contribute to the increased vulnerability to sudden death observed in Familial Dysautonomia.