Vagal and sympathetic heart rate and blood pressure control in adult onset PHOX2B mutation-confirmed congenital central hypoventilation syndrome.
BACKGROUND
Children with Congenital Central Hypoventilation Syndrome (CCHS) typically present as newborns with alveolar hypoventilation. With the advent of genetic testing, parents of affected children and other unrelated adults, all heterozygous for the disease-defining PHOX2B polyalanine expansion mutation with the 20/25 genotype, are being identified in adulthood. Though children with PHOX2B mutation-confirmed CCHS demonstrate ANS dysregulation, including altered heart rate and blood pressure control, it is unknown if adults with CCHS have similarly affected autonomic function in blood pressure control.


RESULTS
An autonomic profile of blood pressure control has been studied with recording of muscle sympathetic activity and spectral analysis of heart rate and blood pressure variability of one adult patient with alveolar hypoventilation and the 20/25 PHOX2B genotype. All parameters of heart rate variability were reduced. Cardiac baroreflex sensitivity was decreased. Sympathetic responses to Valsalva maneuver, hypoxemia, isometric exercise and cold pressor were blunted.


CONCLUSIONS
In summary, we found a reduced cardiac baroreflex and a blunted sympathetic mediated response in the individual with adult-onset CCHS, possibly due to dysfunction in the afferent pathway. Our results confirm that PHOX2B affects the development of the autonomic nervous system, possibly causing absence of normal maturation of carotid body and visceral sensory ganglia and leading to autonomic dysfunction in adult-onset CCHS.
Diedrich
André
A
Dept. of Medicine, Division of Clinical Pharmacology, Autonomic Dysfunction Center, Vanderbilt University School of Medicine, Nashville, TN, USA. andre.diedrich@vanderbilt.edu
Malow
Beth A
BA
Antic
Nick A
NA
Sato
Kyoko
K
McEvoy
R Doug
RD
Mathias
Christopher J
CJ
Robertson
David
D
Berry-Kravis
Elizabeth M
EM
Weese-Mayer
Debra E
DE
D000328:Adult; D017704:Baroreflex / Q000502:physiology; D001794:Blood Pressure / Q000502:physiology*; D002395:Catecholamines / Q000097:blood; D005260:Female; D005838:Genotype; D006334:Heart Function Tests; D006339:Heart Rate / Q000502:physiology*; D018398:Homeodomain Proteins / Q000235:genetics* / Q000502:physiology; D006801:Humans; D009154:Mutation; D012129:Respiratory Function Tests; D020182:Sleep Apnea, Central / Q000151:congenital / Q000235:genetics / Q000503:physiopathology*; D013564:Sympathetic Nervous System / Q000503:physiopathology*; D013577:Syndrome; D014157:Transcription Factors / Q000235:genetics* / Q000502:physiology; D014630:Vagus Nerve / Q000503:physiopathology*
D002395:Catecholamines; D018398:Homeodomain Proteins; C109220:NBPhox protein; D014157:Transcription Factors