Congenital central hypoventilation syndrome with Hirschsprung's disease, also known as Haddad syndrome, is an extremely rare disorder with variable symptoms. Recent studies described that congenital central hypoventilation syndrome had deep relation to the mutation of the PHOX2B gene in its diagnosis and phenotype. We report a newborn male infant with clinical manifestations of recurrent hypoventilation with hypercapnea and bowel obstruction. These clinical manifestations were compatible with congenital central hypoventilation syndrome and Hirschsprung's disease, and polyalanine 26 repeats in the PHOX2B gene supported the diagnosis of congenital central hypoventilation. We described a first case of Haddad syndrome in Korean and its clinical and genetic characteristics were discussed.
Asian Continental Ancestry Group ; Base Sequence ; DNA Mutational Analysis ; Hirschsprung Disease/diagnosis/genetics/pathology ; Homeodomain Proteins/*genetics ; Humans ; Hypoventilation/congenital/diagnosis/genetics ; Infant, Newborn ; Male ; Molecular Sequence Data ; *Mutation ; Sleep Apnea, Central/diagnosis/genetics ; Transcription Factors/*genetics

OBJECTIVETo evaluate clinical characteristics and PHOX2B gene mutations in congenital central hypoventilation syndrome (CCHS) and to facilitate the early diagnosis and management of CCHS and reduce the misdiagnosis.

METHODClinical data of 3 infants with CCHS who had recurrent respiratory failure episodes and dependent on mechanical ventilation support in 3 from March 2008 to April 2012 were analyzed, and blood gas analysis was performed respectively in the awaken and sleeping status. Gene sequencing was used for detection of PHOX2B gene mutation.

RESULTAll the three patients had adequate ventilation during awaken time, but they presented with abnormal frequency and shallow breathing associated with alveolar hypoventilation after falling asleep. Blood gas analysis showed hypercapnia and CO2 partial pressure was consistently over 60 mm Hg (1 mm Hg = 0.133 kPa) after falling asleep, which is in accordance with the clinical features of CCHS. The PHOX2B gene sequencing showed that 6 GCN repeats were inserted at exon3 of PHOX2B in case 1, at same position, 5 GCN repeats were inserted in case 2 and 3.

CONCLUSIONNormal ventilation in awaken status while shallow slow breathing accompanied with hypercapnia in sleep are the main clinical characteristics of CCHS, which requires mechanical ventilation. Acquired mutation in exon 3 of PHOX2B gene encoding repeated GCN sequence seems to be the molecular etiology of these three patients.

Alanine ; genetics ; Blood Gas Analysis ; Carbon Dioxide ; blood ; DNA Mutational Analysis ; Exons ; Female ; Homeodomain Proteins ; genetics ; Humans ; Hypercapnia ; diagnosis ; etiology ; Hypoventilation ; congenital ; diagnosis ; genetics ; therapy ; Infant ; Infant, Newborn ; Male ; Mutation ; Oxygen Inhalation Therapy ; Polymerase Chain Reaction ; Polysomnography ; Respiration, Artificial ; Retrospective Studies ; Sleep Apnea, Central ; diagnosis ; genetics ; therapy ; Transcription Factors ; genetics