Journal of Molecular Medicine

, Volume 89, Issue 5, pp 505–513 | Cite as

Low amounts of PHOX2B expanded alleles in asymptomatic parents suggest unsuspected recurrence risk in congenital central hypoventilation syndrome

  • Tiziana Bachetti
  • Sara Parodi
  • Marco Di Duca
  • Giuseppe Santamaria
  • Roberto Ravazzolo
  • Isabella Ceccherini
Original Article


Heterozygous trinucleotide in frame duplications, leading to expansions of variable lengths of a 20-alanine stretch (polyAla), is the most frequent PHOX2B variant associated with congenital central hypoventilation syndrome (CCHS), a rare neurocristopathy characterized by defective response of the autonomic nervous system to hypoxia and hypercapnia. Sequencing analysis has shown that the vast majority of polyAla expansions arise de novo; while in about 10% of cases, mutations are inherited by one parent who carries either constitutive or somatic mutations. To investigate transmission of PHOX2B mutant alleles from asymptomatic individuals, we have reassessed 44 parental pairs, previously resulted not to carry any mutation, by coupling amplification with FAM-tagged primers and capillary electrophoresis. Low levels of somatic mosaicism were shown in five parents previously undetected, thus increasing the inherited occurrence of the disease from 10% to 25% of the cases. Analysis of the technical detection limits has confirmed a power of resolution much higher for the “FAM” protocol than for the “sequencing” method. These observations are going to have relevant implications on how the carrier status of asymptomatic parents should be assessed and on successive genetic counseling to CCHS families.


PHOX2B CCHS PolyAla expansions Mosaicism Capillary electrophoresis Genetic counseling 



We are extremely grateful to all the families participating in this study and clinicians who have reported patients and provided blood samples to us.

The financial support of Fondazione Mariani (grant#08/69 to I.C.) and of the Ministry of Health (Progetti Finalizzato 2006 and Strategico 2009 to I.C.) are gratefully acknowledged.

Conflict of interest

The authors declare that they have no conflict of interests.

Supplementary material

109_2010_718_MOESM1_ESM.doc (782 kb)
ESM 1(DOC 782 kb)


  1. 1.
    Weese-Mayer DE, Berry-Kravis EM, Ceccherini I, Keens TG, Loghmanee DA, Trang H (2010) An official ATS clinical policy statement: congenital central hypoventilation syndrome: genetic basis, diagnosis, and management. Am J Respir Crit Care Med 181:626–644PubMedCrossRefGoogle Scholar
  2. 2.
    Amiel J, Laudier B, Attiè-Bitach T, Trang H, de Pontual L, Gener B, Trochet D, Etchevers H, Ray P, Simonneau M et al (2003) Polyalanine expansion and frameshift mutations of the paired-like homeobox gene PHOX2B in congenital central hypoventilation syndrome. Nat Genet 33:459–461PubMedCrossRefGoogle Scholar
  3. 3.
    Sasaki A, Kanai M, Kijima K, Akaba K, Hashimoto M, Otaki S, Koizumi T, Kusuda S, Ogawa Y, Tuchiya K et al (2003) Molecular analysis of congenital central hypoventilation syndrome. Hum Genet 114:22–26PubMedCrossRefGoogle Scholar
  4. 4.
    Weese-Mayer DE, Berry-Kravis EM, Zhou L, Maher BS, Silvestri JM, Curran ME, Marazita ML (2003) Idiopathic congenital central hypoventilation syndrome: analysis of genes pertinent to early autonomic nervous system embryologic development and identification of mutations in PHox2b. Am J Med Genet 123:267–278CrossRefGoogle Scholar
  5. 5.
    Matera I, Bachetti T, Puppo F, Di Duca M, Morandi F, Casiraghi GM, Cilio MR, Hennekam R, Hofstra R, Schöber JG et al (2004) PHOX2B mutations and polyalanine expansions correlate with the severity of the respiratory phenotype and associated symptoms in both congenital and late onset Central Hypoventilation syndrome. J Med Genet 41:373–380PubMedCrossRefGoogle Scholar
  6. 6.
    Bachetti T, Matera I, Borghini S, Di Duca M, Ravazzolo R, Ceccherini I (2005) Distinct pathogenetic mechanisms for PHOX2B associated polyalanine expansions and frameshift mutations in congenital central hypoventilation syndrome. Hum Mol Genet 14:1815–1824PubMedCrossRefGoogle Scholar
  7. 7.
    Trochet D, Hong SJ, Lim JK, Brunet JF, Munnich A, Kim KS, Goridis C, Amiel J (2005) Molecular consequences of PHOX2B missense, frameshift and alanine expansion mutations leading to autonomic dysfunction. Hum Mol Genet 14:3697–3708PubMedCrossRefGoogle Scholar
  8. 8.
    Bachetti T, Bocca P, Borghini S, Matera I, Prigione I, Ravazzolo R, Ceccherini I (2007) Geldanamycin promotes nuclear localisation and clearance of PHOX2B misfolded proteins containing polyalanine expansions. Int J Biochem Cell Biol 39:327–339PubMedCrossRefGoogle Scholar
  9. 9.
    Trochet D, O'Brien LM, Gozal D, Trang H, Nordenskjöld A, Laudier B, Svensson PJ, Uhrig S, Cole T, Munnich A et al (2005) PHOX2B genotype allows for prediction of tumor risk in congenital central hypoventilation syndrome. Am J Hum Genet 76:421–426PubMedCrossRefGoogle Scholar
  10. 10.
    Berry-Kravis EM, Zhou L, Rand CM, Weese-Mayer DE (2006) Congenital central hypoventilation syndrome: PHOX2B mutations and phenotype. Am J Respir Crit Care Med 174:1139–1144PubMedCrossRefGoogle Scholar
  11. 11.
    Parodi S, Bachetti T, Lantieri F, Di Duca M, Santamaria G, Ottonello G, Matera I, Ravazzolo R, Ceccherini I (2008) Parental origin and somatic mosaicism of PHOX2B mutations in congenital central hypoventilation syndrome. Hum Mut 29:206PubMedCrossRefGoogle Scholar
  12. 12.
    Trochet D, de Pontual L, Straus C, Gozal D, Trang H, Landrieu P, Lyonnet S, Gaultier C, Amiel J (2005) PHOX2B germline and somatic mutations in late-onset central hypoventilation syndrome. Am J Resp Crit Care Med 177:906–911CrossRefGoogle Scholar
  13. 13.
    Parodi S, Vollono C, Baglietto MP, Balestri M, Di Duca M, Landri PA, Ceccherini I, Ottonello G, Cilio MR (2010) Congenital central hypoventilation syndrome: genotype–phenotype correlation in parents of affected children carrying a PHOX2B expansion mutation. Clin Genet 78:289–293PubMedCrossRefGoogle Scholar
  14. 14.
    Hantash FM, Goos DG, Tsao D, Quan F, Buller-Burckle A, Peng M, Jarvis M, Sun W, Strom CM (2010) Qualitative assessment of FMR1 (CGG)n triplet repeat status in normal, intermediate, premutation, full mutation, and mosaic carriers in both sexes: implications for fragile X syndrome carrier and newborn screening. Genet Med 12:162–173PubMedCrossRefGoogle Scholar
  15. 15.
    Filipovic-Sadic S, Sah S, Krosting J, Sekinger E, Zhang W, Hagerman PJ, Stenzel T, Hadd AG, Latham GJ, Tassone F (2010) A novel FMR1 PCR method for the routine detection of low abundance of expanded alleles and full mutations in fragile X syndrome. Clin Chem 56:399–408PubMedGoogle Scholar
  16. 16.
    Partington MW, Turner G, Boyle J, Gecz J (2004) Three new families with X-linked mental retardation caused by the 428–451dup(24 bp) mutation in ARX. Clin Genet 66:39–45PubMedCrossRefGoogle Scholar
  17. 17.
    Poirier K, Abriol J, Souville I, Laroche-Raynaud C, Beldjord C, Gilbert B, Chelly J, Bienvenu T (2005) Maternal mosaicism for mutations in the ARX gene in a family with X linked mental retardation. HumGenet 118:45–48CrossRefGoogle Scholar
  18. 18.
    Nawara M, Szczaluba K, Poirier K, Chrzanowska K, Pilch J, Bal J, Chelly J, Mazurczak T (2006) The ARX mutations: a frequent cause of X-linked mental retardation. Am J Med Genet A 140A:727–732CrossRefGoogle Scholar
  19. 19.
    Reish O, Fullston T, Regev M, Heyman E, Gecz J (2009) A novel de novo 27 bp duplication of the ARX gene, resulting from postzygotic mosaicism and leading to three severely affected males in two generations. Am J Med Genet A 49:1655–1660Google Scholar
  20. 20.
    Arai H, Otagiri T, Sasaki A, Hashimoto T, Umetsu K, Tokunaga K, Hayasaka K (2007) De novo polyalanine expansion of PHOX2B in congenital central hypoventilation syndrome: unequal sister chromatid exchange during paternal gametogenesis. J Hum Genet 52:921–925PubMedCrossRefGoogle Scholar
  21. 21.
    Trochet D, de Pontual L, Keren B, Munnich A, Vekemans M, Lyonnet S, Amiel J (2007) Polyalanine expansions might not result from unequal crossing-over. Hum Mutat 28:1043–1044PubMedCrossRefGoogle Scholar

Copyright information

© Springer-Verlag 2010

Authors and Affiliations

  • Tiziana Bachetti
    • 1
  • Sara Parodi
    • 1
  • Marco Di Duca
    • 2
  • Giuseppe Santamaria
    • 1
  • Roberto Ravazzolo
    • 1
    • 3
  • Isabella Ceccherini
    • 1
  1. 1.Laboratorio di Genetica MolecolareIstituto Giannina GasliniGenovaItaly
  2. 2.Laboratorio di Fisiopatologia dell’UremiaIstituto Giannina GasliniGenovaItaly
  3. 3.Dipartimento di PediatriaUniversità degli Studi di GenovaGenovaItaly

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