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Pediatric pulmonology · Feb 2014
Case ReportsHeterozygous 24-polyalanine repeats in the PHOX2B gene with different manifestations across three generations.
- Piyaporn Chuen-im, Shinawi Marwan, Jodi Carter, James Kemp, and Katherine Rivera-Spoljaric.
- Department of Pediatrics, Washington University School of Medicine in St. Louis, St. Louis, Missouri.
- Pediatr. Pulmonol. 2014 Feb 1; 49 (2): E13-6.
AbstractCongenital central hypoventilation syndrome (CCHS) is an uncommon genetic disorder that is characterized by alveolar hypoventilation and autonomic dysregulation. More than 90% of the patients are heterozygous for polyalanine repeat expansion mutations in the paired-like homeobox 2b (PHOX2B) gene. The normal genotype has a 20-polyalanine sequence whereas expanded alleles are usually 25-33. Heterozygous 24-polyalanine repeat expansion mutation in the PHOX2B gene has rarely been reported. We report three consecutive generations harboring heterozygous 24-polyalanine repeats in the PHOX2B gene with manifestations ranging from apparently asymptomatic to alveolar hypoventilation and apnea requiring mechanical ventilation. The 3-year-old proband developed cor pulmonale and central hypoventilation following an upper respiratory tract infection. Our findings add to the accumulating evidence that the 24-polyalanine repeat in the PHOX2B is a disease-causing mutation. In addition, a high index of suspicion and careful monitoring after anesthesia, sedation, or respiratory illnesses should be exercised when evaluating asymptomatic family members with this genotype.© 2013 Wiley Periodicals, Inc.
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