Журнал генетических синдромов и генной терапии
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Novel Mutation-Deletion in the PHOX2B Gene of the Patient Diagnosed with Neuroblastoma, Hirschsprungs Disease, and Congenital Central Hypoventilation Syndrome (NB-HSCR- CCHS) Cluster

Izabela Szymonska, Thore Langfeldt Borgenvik, Tina Margrethe Karlsvik, Anders Halsen, Bianka Kathryn Malecki, Sindre Ervik Saetre, Mateusz Jagla, Piotr Kruczek, Anna Madetko Talowska, Grazyna Drabik, Magdalena Zasada and Marek Malecki

Introduction: Neuroblastoma (NB), Hirschsprung disease (HSCR), Congenital Central Hypoventilation Syndrome (CCHS), clinically referred as the NB-HSCR-CCHS cluster, is genetic disorders linked to mutations in the PHOX2B gene on chromosome 4p12. Specific aim: The specific aim of this project is to define the PHOX2B gene mutations as the genomic basis for the clinical manifestations of the NB-HSCR-CCHS cluster. Patient: A one day old male patient presented to the JUMC neonatal ICU due to abdominal distention, vomiting, and severe apneic episodes. With the preliminary diagnosis of the NB-HSCR-CCHS, the blood and tissue samples were acquired from the child, as well as from the child’s parents. All procedures were pursued in accordance with the Declaration of Helsinki, with the patient’s Guardian Informed Consent and the approval from the Institutional Review Board. Genetic/genomic methods: Karyotyping was analyzed based upon Giemsa banding. The patient’s genomic DNA was extracted from peripheral blood and amplified by polymerase chain reaction. Direct microfluidic Sanger sequencing was performed on the genomic DNA amplicons. These procedures were pursued in addition to the routine clinical examinations and tests. Results: G-banding showed the normal 46 XY karyotype. However, genomic sequencing revealed a novel, heterozygous deletion (8 nucleotides (c.699-706, del8) in exon 3 of the PHOX2B gene on chromosome 4. This led to the frame-shift mutation and malfunctioning gene expression product. Conclusion: Herein, we report a novel PHOX2B gene mutation in the patient diagnosed with the NB-HSCRCCHS cluster. The resulting gene expression product may be a contributor to the clinical manifestations of these genetic disorders. It adds to the library of the mutations linked to this syndrome. Consequently, we suggest that screening for the PHOX2B mutations becomes an integral part of genetic counseling, prenatal screening, and preparing supportive therapy upon delivery.