Molecular Medicine

, Volume 21, Issue 1, pp 257–275 | Cite as

A Genotypic-Oriented View of CFTR Genetics Highlights Specific Mutational Patterns Underlying Clinical Macrocategories of Cystic Fibrosis

  • Marco Lucarelli
  • Sabina Maria Bruno
  • Silvia Pierandrei
  • Giampiero Ferraguti
  • Antonella Stamato
  • Fabiana Narzi
  • Annalisa Amato
  • Giuseppe Cimino
  • Serenella Bertasi
  • Serena Quattrucci
  • Roberto Strom
Research Article


Cystic fibrosis (CF) is a monogenic disease caused by mutations of the cystic fibrosis transmembrane conductance regulator (CFTR) gene. The genotype-phenotype relationship in this disease is still unclear, and diagnostic, prognostic and therapeutic challenges persist. We enrolled 610 patients with different forms of CF and studied them from a clinical, biochemical, microbiological and genetic point of view. Overall, there were 125 different mutated alleles (11 with novel mutations and 10 with complex mutations) and 225 genotypes. A strong correlation between mutational patterns at the genotypic level and phenotypic macrocategories emerged. This specificity appears to largely depend on rare and individual mutations, as well as on the varying prevalence of common alleles in different clinical macrocategories. However, 19 genotypes appeared to underlie different clinical forms of the disease. The dissection of the pathway from the CFTR mutated genotype to the clinical phenotype allowed to identify at least two components of the variability usually found in the genotype-phenotype relationship. One component seems to depend on the genetic variation of CFTR, the other component on the cumulative effect of variations in other genes and cellular pathways independent from CFTR. The experimental dissection of the overall biological CFTR pathway appears to be a powerful approach for a better comprehension of the genotype-phenotype relationship. However, a change from an allele-oriented to a genotypic-oriented view of CFTR genetics is mandatory, as well as a better assessment of sources of variability within the CFTR pathway.



Approximately 29% of the patients included in this case series, because enrolled at the CF Reference Center of Lazio (Italy) Region, were preliminarily studied by several Italian Centers from the mutational point of view by means of approaches limited to panels of the most frequent CFTR mutations. This preliminary characterization was performed as follows: 59 patients from the medical genetics section of the “Dipartimento di Biomedicina e Prevenzione, Università Tor Vergata” (Rome), 48 patients from the neonatal screening center of the “Croce Rossa Italiana” (Rome), 37 patients from the neonatal screening center of the “Dipartimento di Medicina Sperimentale, Sapienza Università di Roma” (Rome), and 32 patients from the medical genetics laboratory of the “Fondazione IRCCS Cà Granda, Ospedale Maggiore Policlinico, Mangiagalli e Regina Elena” (Milan). In about half of these patients, at least one allele with no mutation was detected. After enrollment, all these patients underwent the mutational search strategy described in Materials and Methods for confirmation of the mutation(s) already found, completion of the mutational search and allele segregation in their parents and/or relatives.

This work was supported by the following grants: Regione Lazio (research projects 2002–2005), Fondazione per la Ricerca sulla Fibrosi Cistica (project 9/2004), Fondazione Telethon (project GGP06199, 2007–2010), Istituto Pasteur Fondazione Cenci Bolognetti (project 2009–2012). S M Bruno was supported by Associazione Laziale Fibrosi Cistica. G Ferraguti was partially supported by Fondazione per la Ricerca sulla Fibrosi Cistica. S Pierandrei was partially supported by Telethon Foundation and by Associazione Laziale Fibrosi Cistica.

This work is dedicated to the late Lorena Narzi, whose great contribution made this study and other CF studies possible.

Supplementary material

10020_2015_2101257_MOESM1_ESM.pdf (13.4 mb)
Supplementary material, approximately 13.3 MB.


  1. 1.
    Lucarelli M, Pierandrei S, Bruno SM, Strom R. (2012) The Genetics of CFTR: Genotype — Phenotype Relationship, Diagnostic Challenge and Therapeutic Implications [Internet]. In: Cystic Fibrosis — Renewed Hopes Through Research. Sriramulu D (ed.) Intech, Rijeka, Croatia, [cited 2015 Jun 15], pp. 91–122. Available from: Scholar
  2. 2.
    Davies JC, Alton EW, Bush A. (2007) Cystic fibrosis. BMJ. 335:1255–9.CrossRefGoogle Scholar
  3. 3.
    O’Sullivan BP, Freedman SD. (2009) Cystic fibrosis. Lancet. 373:1891–904.CrossRefGoogle Scholar
  4. 4.
    Riordan JR. (2008) CFTR function and prospects for therapy. Annu. Rev. Biochem. 77:701–26.CrossRefGoogle Scholar
  5. 5.
    Drumm ML, Ziady AG, Davis PB. (2012) Genetic variation and clinical heterogeneity in cystic fibrosis. Annu. Rev. Pathol. 7:267–82.CrossRefGoogle Scholar
  6. 6.
    Paranjape SM, Zeitlin PL. (2008) Atypical cystic fibrosis and CFTR-related diseases. Clin. Rev. Allergy Immunol. 35:116–23.CrossRefGoogle Scholar
  7. 7.
    Dequeker E, et al. (2009) Best practice guidelines for molecular genetic diagnosis of cystic fibrosis and CFTR-related disorders: updated European recommendations. Eur. J. Hum. Genet. 17:51–65.CrossRefGoogle Scholar
  8. 8.
    Bombieri C, et al. (2011) Recommendations for the classification of diseases as CFTR-related disorders. J. Cyst. Fibros. 10 Suppl 2:S86–102.CrossRefGoogle Scholar
  9. 9.
    Bombieri C, Seia M, Castellani C (2015) Genotypes and phenotypes in cystic fibrosis and cystic fibrosis transmembrane regulator-related disorders. Semin. Respir. Crit. Care Med. 36:180–93.CrossRefGoogle Scholar
  10. 10.
    Cystic Fibrosis Mutation Database [Internet]. [updated 2011 Apr 25; cited 2015 June 22]. Available from:
  11. 11.
    Sosnay PR, et al. (2013) Defining the disease liability of variants in the cystic fibrosis transmembrane conductance regulator gene. Nat. Genet. 45:1160–7.CrossRefGoogle Scholar
  12. 12.
    Amaral MD, Kunzelmann K. (2007) Molecular targeting of CFTR as a therapeutic approach to cystic fibrosis. Trends Pharmacol. Sci. 28:334–41.CrossRefGoogle Scholar
  13. 13.
    Becq F, Mall MA, Sheppard DN, Conese M, Zegarra-Moran O. (2011) Pharmacological therapy for cystic fibrosis: from bench to bedside. J. Cyst. Fibros. 10(Suppl 2):S129–45.CrossRefGoogle Scholar
  14. 14.
    Rogan MP, Stoltz DA, Hornick DB. (2011) Cystic fibrosis transmembrane conductance regulator intracellular processing, trafficking, and opportunities for mutation-specific treatment. Chest. 139:1480–90.CrossRefGoogle Scholar
  15. 15.
    Borowitz D, et al. (2009) Cystic Fibrosis Foundation evidence-based guidelines for management of infants with cystic fibrosis. J. Pediatr. 155:S73–93.CrossRefGoogle Scholar
  16. 16.
    Canton R, et al. (2005) Antimicrobial therapy for pulmonary pathogenic colonisation and infection by Pseudomonas aeruginosa in cystic fibrosis patients. Clin. Microbiol. Infect. 11:690–703.CrossRefGoogle Scholar
  17. 17.
    Farrell PM, et al. (2008) Guidelines for diagnosis of cystic fibrosis in newborns through older adults: Cystic Fibrosis Foundation consensus report. J. Pediatr. 153:S4–14.CrossRefGoogle Scholar
  18. 18.
    Miller MB, Gilligan PH. (2003) Laboratory aspects of management of chronic pulmonary infections in patients with cystic fibrosis. J. Clin. Microbiol. 41:4009–15.CrossRefGoogle Scholar
  19. 19.
    Zhou J, Garber E, Desai M, Saiman L. (2006) Compliance of clinical microbiology laboratories in the United States with current recommendations for processing respiratory tract specimens from patients with cystic fibrosis. J. Clin. Microbiol. 44:1547–9.CrossRefGoogle Scholar
  20. 20.
    Castellani C, et al. (2009) European best practice guidelines for cystic fibrosis neonatal screening. J. Cyst. Fibros. 8:153–73.CrossRefGoogle Scholar
  21. 21.
    Gibson LE, Cooke RE. (1959) A test for concentration of electrolytes in sweat in cystic fibrosis of the pancreas utilizing pilocarpine by iontophoresis. Pediatrics. 23:545–9.PubMedGoogle Scholar
  22. 22.
    Gullo L, et al. (1997) Faecal elastase 1 in children with cystic fibrosis. Eur. J. Pediatr. 156:770–2.CrossRefGoogle Scholar
  23. 23.
    Lucarelli M, et al. (2002) Simultaneous cycle sequencing assessment of (TG)m and Tn tract length in CFTR gene. Biotechniques. 32:540–7.CrossRefGoogle Scholar
  24. 24.
    Lucarelli M, et al. (2006) A 96-well formatted method for exon and exon/intron boundary full sequencing of the CFTR gene. Anal. Biochem. 353:226–35.CrossRefGoogle Scholar
  25. 25.
    Ferraguti G, et al. (2011) A template for mutational data analysis of the CFTR gene. Clin. Chem. Lab Med. 49:1447–51.CrossRefGoogle Scholar
  26. 26.
    Narzi L, et al. (2002) Comparison of two different protocols of neonatal screening for cystic fibrosis. Clin. Genet. 62:245–9.CrossRefGoogle Scholar
  27. 27.
    Narzi L, et al. (2007) Does cystic fibrosis neonatal screening detect atypical CF forms? Extended genetic characterization and 4-year clinical followup. Clin. Genet. 72:39–46.CrossRefGoogle Scholar
  28. 28.
    Lucarelli M, et al. (2010) A new complex allele of the CFTR gene partially explains the variable phenotype of the L997F mutation. Genet. Med. 12:548–55.CrossRefGoogle Scholar
  29. 29.
    Teixeira S, et al. (2013) Immunohistochemical analysis of CFTR in normal and disrupted spermatogenesis. Syst. Biol. Reprod. Med. 59:53–9.CrossRefGoogle Scholar
  30. 30.
    Dube E, Hermo L, Chan PT, Cyr DG. (2008) Alterations in gene expression in the caput epididymides of nonobstructive azoospermic men. Biol. Reprod. 78:342–51.CrossRefGoogle Scholar
  31. 31.
    Patrizio P, Salameh WA. (1998) Expression of the cystic fibrosis transmembrane conductance regulator (CFTR) mRNA in normal and pathological adult human epididymis. J. Reprod. Fertil. Suppl 53:261–70.PubMedGoogle Scholar
  32. 32.
    Xu WM, et al. (2011) Defective CFTR-dependent CREB activation results in impaired spermatogenesis and azoospermia. PLoS One. 6:e19120.CrossRefGoogle Scholar
  33. 33.
    Chen MH, et al. (2010) Involvement of CFTR in oviductal. Hum. Reprod. 25:1744–54.CrossRefGoogle Scholar
  34. 34.
    Muchekehu RW, Quinton PM. (2010) A new role for bicarbonate secretion in cervico-uterine mucus release. J. Physiol. 588:2329–42.CrossRefGoogle Scholar
  35. 35.
    Hodges CA, Palmert MR, Drumm ML. (2008) Infertility in females with cystic fibrosis is multifactorial: evidence from mouse models. Endoerinology. 149:2790–7.CrossRefGoogle Scholar
  36. 36.
    Trezise AE, et al. (1993) CFTR expression is regulated during both the cycle of the seminiferous epithelium and the oestrous cycle of rodents. Nat. Genet. 3:157–64.CrossRefGoogle Scholar
  37. 37.
    Yu J, et al. (2011) Association of genetic variants in CFTR gene, IVS8 c.1210-12T[5_9] and c.1210-35_1210-12GT[8_12], with spermatogenetic failure: case-control study and meta-analysis. Mol. Hum. Reprod. 17:594–603.CrossRefGoogle Scholar
  38. 38.
    Claustres M. (2005) Molecular pathology of the CFTR locus in male infertility. Reprod. Biomed. Online. 10:14–41.CrossRefGoogle Scholar
  39. 39.
    Dohle GR, et al. (2002) Genetic risk factors in infertile men with severe oligozoospermia and azoospermia. Hum. Reprod. 17:13–6.CrossRefGoogle Scholar
  40. 40.
    Elia J, et al. (2009) Human semen hyperviscosity: prevalence, pathogenesis and therapeutic aspects. Asian J. Androl 11:609–15.CrossRefGoogle Scholar
  41. 41.
    Rossi T, et al. (2004) High frequency of (TG)mTn variant tracts in the cystic fibrosis transmembrane conductance regulator gene in men with high semen viscosity. Fertil. Steril. 82:1316–22.CrossRefGoogle Scholar
  42. 42.
    Ahmad A, Ahmed A, Patrizio P. (2013) Cystic fibrosis and fertility. Curr. Opin. Obstet. Gyneeol. 25:167–72.CrossRefGoogle Scholar
  43. 43.
    Gervais R, et al. (1996) Hypofertility with thick cervical mucus: another mild form of cystic fibrosis? JAMA. 276:1638.CrossRefGoogle Scholar
  44. 44.
    Schoyer KD, Gilbert F, Rosenwaks Z. (2008) Infertility and abnormal cervical mucus in two sisters who are compound heterozygotes for the cystic fibrosis (CF) DeltaF508 and R117H/7T mutations. Fertil. Steril. 90:1201–22.CrossRefGoogle Scholar
  45. 45.
    Leoni GB, et al. (1995) A specific cystic fibrosis mutation (T338I) associated with the phenotype of isolated hypotonic dehydration. J. Pediatr. 127:281–3.CrossRefGoogle Scholar
  46. 46.
    Padoan R, Seia M, Cremonesi L, Giunta A. (1996) Mild CF phenotype associated with T338I missense mutation. J. Pediatr. 128:721–2.CrossRefGoogle Scholar
  47. 47.
    Cutting GR. (2010) Modifier genes in Mendelian disorders: the example of cystic fibrosis. Ann. N. Y. Acad. Sei. 1214:57–69.CrossRefGoogle Scholar
  48. 48.
    Gisler FM, von KT, Kraemer R, Schaller A, Gallati S. (2013) Identification of SNPs in the cystic fibrosis interactome influencing pulmonary progression in cystic fibrosis. Eur. J. Hum. Genet. 21:397–403.CrossRefGoogle Scholar
  49. 49.
    Wang X, et al. (2006) Hsp90 cochaperone Aha1 downregulation rescues misfolding of CFTR in cystic fibrosis. Cell. 127:803–15.CrossRefGoogle Scholar

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Authors and Affiliations

  • Marco Lucarelli
    • 1
    • 2
    • 3
  • Sabina Maria Bruno
    • 1
  • Silvia Pierandrei
    • 1
    • 2
  • Giampiero Ferraguti
    • 1
  • Antonella Stamato
    • 3
    • 4
    • 5
  • Fabiana Narzi
    • 3
    • 4
    • 5
  • Annalisa Amato
    • 3
    • 4
    • 5
  • Giuseppe Cimino
    • 3
    • 5
  • Serenella Bertasi
    • 3
    • 5
  • Serena Quattrucci
    • 3
    • 4
    • 5
  • Roberto Strom
    • 1
    • 3
  1. 1.Department of Cellular Biotechnologies and HematologySapienza University of RomeRomeItaly
  2. 2.Pasteur Institute, Cenci Bolognetti FoundationSapienza University of RomeRomeItaly
  3. 3.Policlinico Umberto I HospitalRomeItaly
  4. 4.Department of PediatricsSapienza University of RomeRomeItaly
  5. 5.Cystic Fibrosis Reference Center of Lazio RegionRomeItaly

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