PHOX2B gene testing is performed by the Molecular Diagnostic Laboratory at Lurie Children's. For the sequencing test, the entire coding region together with the intronic splice sites are sequenced and analyzed. This test detects polyalanine-repeat mutations as well as known and novel non-polyalanine repeat mutations.
Deletions of PHOX2B have recently been associated with Congenital Central Hypoventilation Syndrome (CCHS)-like symptoms, although the genotype-phenotype association is not yet clear. An estimated 2-5% of PHOX2B mutations will be a large deletion of the entire gene or part of the gene that cannot be detected by sequencing. Therefore, we have validated another technique to detect deletions and duplications in PHOX2B called Multiplex Ligation-Dependent Probe Amplification (MLPA). All identified deletion/duplication abnormalities are also tested by high-density array comparative genomic hybridization to better define the region involved.