Background The effect of complex alleles in cystic fibrosis (CF) is poorly defined for the lack of functional studies. Objectives To describe the genotype-phenotype correlation and the results of either in vitro and ex vivo studies performed on nasal epithelial cells (NEC) in a cohort of patients with CF carrying cystic fibrosis transmembrane conductance regulator (CFTR) complex alleles. Methods We studied 70 homozygous, compound heterozygous or heterozygous for CFTR mutations: p. [Arg74Trp;Val201Met;Asp1270Asn], n=8; p.[Ile148Thr; Ile1023_Val1024del], n=5; p.[Arg117Leu;Leu997Phe], n=6; c.[1210-34TG[12];1210-12T[5];2930C>T], n=3; p. [Arg74Trp;Asp1270Asn], n=4; p.Asp1270Asn, n=2; p. Ile148Thr, n=6; p.Leu997Phe, n=36. In 39 patients, we analysed the CFTR gating activity on NEC in comparison with patients with CF (n=8) and carriers (n=4). Finally, we analysed in vitro the p.[Arg74Trp;Val201Met;Asp1270Asn] complex allele. Results The p.[Ile148Thr;Ile1023_Val1024del] caused severe CF in five compound heterozygous with a class I-II mutation. Their CFTR activity on NEC was comparable with patients with two class I-II mutations (mean 7.3% vs 6.9%). The p.[Arg74Trp;Asp1270Asn] and the p. Asp1270Asn have scarce functional effects, while p. [Arg74Trp;Val201Met;Asp1270Asn] caused mild CF in four of five subjects carrying a class I-II mutation in trans, or CFTR-related disorders (CFTR-RD) in three having in trans a class IV-V mutation. The p.[Arg74Trp;Val201Met; Asp1270Asn] causes significantly (p<0.001) higher CFTR activity compared with compound heterozygous for class I-II mutations. Furthermore, five of six compounds heterozygous with the p.[Arg117Leu;Leu997Phe] had mild CF, whereas the p.Leu997Phe, in trans with a class I-II CFTR mutation, caused CFTR-RD or a healthy status (CFTR activity: 21.3-36.9%). Finally, compounds heterozygous for the c.[1210-34TG[12];1210-12T[5];2930C>T] and a class I-II mutation had mild CF or CFTR-RD (gating activity: 18.5-19.0%). Conclusions The effect of complex alleles partially depends on the mutation in trans. Although larger studies are necessary, the CFTR activity on NEC is a rapid contributory tool to classify patients with CFTR dysfunction.

Genotype-phenotype correlation and functional studies in patients with cystic fibrosis bearing CFTR complex alleles / V. Terlizzi, G. Castaldo, D. Salvatore, M. Lucarelli, V. Raia, A. Angioni, V. Carnovale, N. Cirilli, R. Casciaro, C. Colombo, A.M. Di Lullo, A. Elce, P. Iacotucci, M. Comegna, M. Scorza, V. Lucidi, A. Perfetti, R. Cimino, S. Quattrucci, M. Seia, V.M. Sofia, F. Zarrilli, F. Amato. - In: JOURNAL OF MEDICAL GENETICS. - ISSN 0022-2593. - 54:4(2017), pp. 224-235. [10.1136/jmedgenet-2016-103985]

Genotype-phenotype correlation and functional studies in patients with cystic fibrosis bearing CFTR complex alleles

C. Colombo;
2017

Abstract

Background The effect of complex alleles in cystic fibrosis (CF) is poorly defined for the lack of functional studies. Objectives To describe the genotype-phenotype correlation and the results of either in vitro and ex vivo studies performed on nasal epithelial cells (NEC) in a cohort of patients with CF carrying cystic fibrosis transmembrane conductance regulator (CFTR) complex alleles. Methods We studied 70 homozygous, compound heterozygous or heterozygous for CFTR mutations: p. [Arg74Trp;Val201Met;Asp1270Asn], n=8; p.[Ile148Thr; Ile1023_Val1024del], n=5; p.[Arg117Leu;Leu997Phe], n=6; c.[1210-34TG[12];1210-12T[5];2930C>T], n=3; p. [Arg74Trp;Asp1270Asn], n=4; p.Asp1270Asn, n=2; p. Ile148Thr, n=6; p.Leu997Phe, n=36. In 39 patients, we analysed the CFTR gating activity on NEC in comparison with patients with CF (n=8) and carriers (n=4). Finally, we analysed in vitro the p.[Arg74Trp;Val201Met;Asp1270Asn] complex allele. Results The p.[Ile148Thr;Ile1023_Val1024del] caused severe CF in five compound heterozygous with a class I-II mutation. Their CFTR activity on NEC was comparable with patients with two class I-II mutations (mean 7.3% vs 6.9%). The p.[Arg74Trp;Asp1270Asn] and the p. Asp1270Asn have scarce functional effects, while p. [Arg74Trp;Val201Met;Asp1270Asn] caused mild CF in four of five subjects carrying a class I-II mutation in trans, or CFTR-related disorders (CFTR-RD) in three having in trans a class IV-V mutation. The p.[Arg74Trp;Val201Met; Asp1270Asn] causes significantly (p<0.001) higher CFTR activity compared with compound heterozygous for class I-II mutations. Furthermore, five of six compounds heterozygous with the p.[Arg117Leu;Leu997Phe] had mild CF, whereas the p.Leu997Phe, in trans with a class I-II CFTR mutation, caused CFTR-RD or a healthy status (CFTR activity: 21.3-36.9%). Finally, compounds heterozygous for the c.[1210-34TG[12];1210-12T[5];2930C>T] and a class I-II mutation had mild CF or CFTR-RD (gating activity: 18.5-19.0%). Conclusions The effect of complex alleles partially depends on the mutation in trans. Although larger studies are necessary, the CFTR activity on NEC is a rapid contributory tool to classify patients with CFTR dysfunction.
Regulator mutation; quality assessment; diagnosis; disorders; gene; frequency; consensus; variants; disease; L997F
Settore MED/38 - Pediatria Generale e Specialistica
2017
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2434/558558
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