A neonate with marked prolonged mixed apneas and CHARGE syndrome: a case report

phox2ba: The Potential Genetic Link behind the Overlap in the Symptomatology between CHARGE and Central Congenital Hypoventilation Syndromes

CHARGE syndrome typically results from mutations in the gene encoding chromodomain helicase DNA-binding protein 7 (CHD7). CHD7 is involved in regulating neural crest development, which gives rise to tissues of the skull/face and the autonomic nervous system (ANS). Individuals with CHARGE syndrome are frequently born with anomalies requiring multiple surgeries and often experience adverse events post-anesthesia, including oxygen desaturations, decreased respiratory rates, and heart rate abnormalities. Central congenital hypoventilation syndrome (CCHS) affects ANS components that regulate breathing. Its hallmark feature is hypoventilation during sleep, clinically resembling observations in anesthetized CHARGE patients. Loss of PHOX2B (paired-like homeobox 2b) underlies CCHS. Employing a chd7-null zebrafish model, we investigated physiologic responses to anesthesia and compared these to loss of phox2b. Heart rates were lower in chd7 mutants compared to the wild-type. Exposure to tricaine, a zebrafish anesthetic/muscle relaxant, revealed that chd7 mutants took longer to become anesthetized, with higher respiratory rates during recovery. chd7 mutant larvae demonstrated unique phox2ba expression patterns. The knockdown of phox2ba reduced larval heart rates similar to chd7 mutants. chd7 mutant fish are a valuable preclinical model to investigate anesthesia in CHARGE syndrome and reveal a novel functional link between CHARGE syndrome and CCHS.

Clinical and Genetic Analysis of CHD7 Expands the Genotype and Phenotype of CHARGE Syndrome

CHARGE syndrome is a life-threatening disease caused by mutations of chromodomain helicase DNA-binding protein 7 gene (CHD7). The disease is characterized by a pattern of congenital anomalies that involve multiple organs. In this study, five patients were diagnosed as CHARGE syndrome with CHD7 mutations by whole exome sequencing. Although the clinical phenotypes of probands are highly variable and typical symptoms such as coloboma and choanal atresia are not commonly manifested in this cohort, they all presented congenital heart defects. Of note, dyspnea is the most prominent symptom in all five neonatal patients, suggesting that dyspnea might be a phenotypic clue of CHARGE syndrome.