ABCMdb

PMID: 15176679

Decaestecker K, Decaestecker E, Castellani C, Jaspers M, Cuppens H, De Boeck K
Genotype/phenotype correlation of the G85E mutation in a large cohort of cystic fibrosis patients.
Eur Respir J. 2004 May;23(5):679-84., [PubMed]

Sentences

No. Mutations Sentence Comment

25 ABCC7 p.Gly85Glu Worldwide, of all mutations reported, the G85E mutation has a frequency y0.2%. Login to comment 27 ABCC7 p.Gly85Glu The G85E mutation is a missense mutation: in exon 3, at nucleotide position 386, guanine is replaced by adenosine, resulting in the substitution of glycine by negatively charged glutamic acid in the first membrane-spanning domain [9]. Login to comment 28 ABCC7 p.Gly85Glu Earlier reports about G85E concern a small number of patients. Login to comment 30 ABCC7 p.Gly85Glu The purpose of the present study was to determine the clinical outcome of CF patients, homozygous or compound heterozygous for the G85E mutation, in a large study group. Login to comment 31 ABCC7 p.Gly85Glu In addition, the effect of G85E mutation constructs on CFTR protein expression was evaluated in in vitro cell lines. Login to comment 33 ABCC7 p.Gly85Glu They were asked to report clinical data on their patients homozygous or compound heterozygous for the G85E mutation and, per index case, on two control CF patients. Login to comment 47 ABCC7 p.Gly85Glu ABCC7 p.Gly85Glu ABCC7 p.Gly85Glu In order to have a clear-cut evaluation of the influence of the G85E mutation, a primary analysis for G85E/F508del patients versus F508del/F508del PI patients was performed. The G85E patients were also compared with the groups with PI and PS. Login to comment 49 ABCC7 p.Gly85Glu From the group of G85E patients, thirteen with unknown second mutation or with a second mutation known to be associated with PS were eliminated. Login to comment 54 ABCC7 p.Gly85Glu ABCC7 p.Gly85Glu Apart from studying the phenotype in patients carrying the G85E mutation, the G85E mutation was expressed in cell lines, and the influence of the mutation on CFTR protein biosynthesis and expression in vitro was studied. Login to comment 55 ABCC7 p.Gly85Glu This technique helps to determine which mutation class G85E belongs to, at least in the chosen expression system [18]. Login to comment 56 ABCC7 p.Gly85Glu G85E-CFTR cDNA/pcDNA3 expression vectors, either on a M470-CFTR or V470-CFTR background, were made by means of the TransformerTM Site-Directed Mutagenesis Kit (Clontech, Palo Alto, CA, USA), using the mutagenesis primer 59-GGA GAT TTA TGT TCT ATG AAA TCT TTT-39, according to previously described protocols [19]. Login to comment 61 ABCC7 p.Gly85Glu Data were collected on the phenotype of 68 patients homozygous or compound heterozygous for the G85E mutation. Login to comment 64 ABCC7 p.Gly85Glu ABCC7 p.Gly85Glu Out of 68 patients in the G85E group, 34 carried the G85E/ F508del mutations. Login to comment 68 ABCC7 p.Gly85Glu One index case was homozygous for the G85E mutation and was PS. Login to comment 69 ABCC7 p.Gly85Glu All but two patients in the G85E group were Caucasian: one was Caucasian/African (Antilles) and one was African. Login to comment 78 ABCC7 p.Gly85Glu ABCC7 p.Gly85Glu G85E/F508del compared to F508del/F508del This analysis concerns 31 patients and is presented in table 2: three of the 34 patients with G85E/F508del genotype in whom the PI control patient did not have a F508del/ F508del genotype were excluded from analysis. Login to comment 80 ABCC7 p.Gly85Glu However, PI was less frequent in the G85E/F508del group. Login to comment 81 ABCC7 p.Gly85Glu In addition, at time of diagnosis, steatorrhea and failure to thrive were less frequent in G85E/ F508del patients. Login to comment 83 ABCC7 p.Gly85Glu ABCC7 p.Gly85Glu ABCC7 p.Gly85Glu G85E patients (with second mutation known and not classified as mild) compared to PI and PS matched controls Comparison of this larger G85E patient group with their PI controls (n=55; table 3) showed the same results as the comparison between the G85E/F508del subgroup versus the F508del/ F508del group. Login to comment 86 ABCC7 p.Gly85Glu ABCC7 p.Gly85Glu Comparison of the G85E group with PS controls (n=44; table 3) showed that the G85E patients have a significantly higher sweat chloride (pv0.0018), more often present symptoms of steatorrhea and failure to thrive at diagnosis (pv0.0001), higher prevalence of pancreatic insufficiency (pv0.0001), worse current weight for height (pv0.02), higher prevalence of chronic P. aeruginosa colonisation (pv0.0083) and liver cirrhosis (pv0.05). Login to comment 87 ABCC7 p.Gly85Glu The most recent FEV1 % pred was 69¡4.8% in the G85E group and 85¡6.6% in the PS group (p=0.08). Login to comment 88 ABCC7 p.Gly85Glu Median age at diagnosis was 22 months in the G85E group and 44 months in the PS group (p=0.13). Login to comment 90 ABCC7 p.Gly85Glu If all G85E patients were considered (n=68) in the analysis, these last differences again reached statistical significance (data not shown). Login to comment 91 ABCC7 p.Gly85Glu Three patients of the G85E group died: two patients died at the age of 10 yrs, of whom one after Burkholderia cepacia colonisation; and one patient died at Table 1. Login to comment 92 ABCC7 p.Glu585* ABCC7 p.Gly85Glu ABCC7 p.Gly85Glu ABCC7 p.Gly85Glu ABCC7 p.Gly85Glu ABCC7 p.Gly85Glu ABCC7 p.Gly85Glu ABCC7 p.Gly85Glu ABCC7 p.Gly85Glu ABCC7 p.Gly85Glu ABCC7 p.Gly85Glu ABCC7 p.Gly85Glu ABCC7 p.Gly85Glu ABCC7 p.Gly85Glu ABCC7 p.Gly85Glu ABCC7 p.Thr338Ile ABCC7 p.Leu1065Pro ABCC7 p.Arg1066Cys ABCC7 p.His139Arg - Cystic fibrosis transmembrane conductance regulator genotypes of patients in the three study groups G85E PI PS Genotype Subjects n Genotype Subjects n Genotype Subjects n G85E/F508del# 34 F508del# /F508del# 58 F508del# /unknown 15 G85E/unknown 8 F508del# /unknown 2 F508del# /3849z10 kbCRT} 5 G85E/G542X# 5 F508del# /1717-1GR A 1 F508del# /R117H} 3 G85E/W1282X# 4 F508del# /N1303K# 1 T338I/L1065P 2 G85E/I507del# 3 F508del*/H139R 1 E585X/3272-26ARG} 2 G85E/R1162X# 3 F508del# /R1066C # 1 2183AARG/2789z5GRA 2 G85E/2183AARG 2 F508del# /G542X# 1 F508del# /711z5GRA 1 G85E/G85E 1 F508del# /712-1GRT 1 F508del# /D1152H} 1 G85E/E585X# 1 F508del# /621z1GRT 1 F508del# /1898z3ARG 1 G85E/711z1GRT# 1 F508del# /1898z1 1 F508del# /R347H} 1 G85E/712-1GRT# 1 Total 68 F508del# /2789z5GRA 1 G85E/621z1GRT# 1 2789z5GRA/? Login to comment 93 ABCC7 p.Arg352Gln ABCC7 p.Leu206Trp ABCC7 p.Leu206Trp ABCC7 p.Gly85Glu ABCC7 p.Gly85Glu ABCC7 p.Gly85Glu ABCC7 p.Gly85Glu ABCC7 p.Arg1158* ABCC7 p.Glu822* ABCC7 p.Trp496* ABCC7 p.Thr388Ile 1 G85E/W496X 1 F508del# /N1303K# 1 G85E/N1303K# 1 T388I/R1158X 1 G85E/711z5GRA} 1 3272-26AwG} /E822X 1 G85E/R334W} 1 F508del# /R334W} 1 Total 68 574delA/2789z5GRA 1 F508del# /3272-26ARG} 1 F508del# /R352Q 1 F508del# /3272-26AwG} 1 R334W} /444delA 1 L206W/3272-26ARG} 1 F508del# /F508del# 1 L206W/? Login to comment 98 ABCC7 p.Gly85Glu ABCC7 p.Gly85Glu ABCC7 p.Gly85Glu - Current age and clinical variables in a group of European cystic fibrosis (CF) patients heterozygous for G85E and F508del compared to CF patients homozygous for F508del G85E/F508del F508del/F508del G85E/F508del versus F508del/F508del Subjects n 31 31 Current age yrs 19.5¡7.2 (2-40) 19.5¡6.9 (3-39) 0.05# Age at time of diagnosis months 5 (2-40) 9 (2.5-23) 0.2} Sweat chloride mEq?L-1 100 (90-110) 100 (88-110) 0.95} Presenting symptoms Steatorrhea 38 86 0.0003z Failure to thrive 38 70 0.017z Meconium ileus 4 7 0.38z Respiratory 82 62 0.88z Pancreatic insufficiency 60 100 v0.001z Most recent weight for height percentile 60¡5 58¡6 0.68# Most recent FEV1 % pred 69¡5 65¡6 0.78# Chronic P. aeruginosa colonisation 41 45 0.33z Complications Liver cirrhosis 13 7 0.119z CF-DM 9 6 0.298z DIOS 16 6 0.16z Pancreatitis n 1 0 0.5z Data are presented as mean¡SD (range), median (interquartile range), mean¡SEM or % unless otherwise stated. Subjects were matched for centre, sex and age. FEV1: forced expiratory volume in one second; pred: predicted; P. aeruginosa: Pseudomonas aeruginosa; CF-RD: cystic fibrosis-related diabetes; DIOS: distal intestinal obstruction syndrome. Statistical analysis by paired t-test# , Wilcoxon signed-ranks test} and Fisher exact testz . Login to comment 100 ABCC7 p.Gly85Glu This further documents the severe lung disease in the G85E patients. Login to comment 101 ABCC7 p.Gly85Glu The frequency of pancreatic insufficiency was 57% in the total G85E group. Login to comment 102 ABCC7 p.Gly85Glu Within the total G85E group, the age of the patients with PI was 23.0¡1.7 yrs and of the patients with PS 16.1¡1.7 yrs. Login to comment 104 ABCC7 p.Gly85Glu Sibling pairs There were six sibling pairs in the G85E group. Login to comment 105 ABCC7 p.Gly85Glu ABCC7 p.Gly85Glu Two sibpairs, all compound heterozygous for the G85E and F508del mutations, were discordant for pancreatic disease manifestation. Login to comment 113 ABCC7 p.Gly85Glu ABCC7 p.Gly85Glu In vitro functional properties of G85E-CFTR The degree of G85E-CFTR maturation was investigated. Login to comment 115 ABCC7 p.Gly85Glu However, the haplotype background of G85E-CFTR genes is mostly unknown. Login to comment 116 ABCC7 p.Gly85Glu G85E was, therefore, studied either on a M470 or V470 background. Login to comment 117 ABCC7 p.Gly85Glu ABCC7 p.Gly85Glu G85E-V470-, G85E-M470- and wildtype-V470-CFTR were transiently expressed in COS cells. Login to comment 119 ABCC7 p.Gly85Glu ABCC7 p.Gly85Glu In contrast, G85E-V470- and G85E-M470-CFTR failed to mature to the complex-glycosylated C-form at all time periods (fig. 1). Login to comment 120 ABCC7 p.Gly85Glu Discussion CF patients with the G85E mutation have a severe phenotype. Login to comment 121 ABCC7 p.Gly85Glu When comparing G85E/F508del and F508del/ F508del patients, there are no differences in age at diagnosis, sweat chloride value, parameters evaluating lung disease, most recent weight for height, nor CF complications. Login to comment 122 ABCC7 p.Gly85Glu Conversely, comparing G85E patients with PS patients it Table 3. Login to comment 123 ABCC7 p.Gly85Glu ABCC7 p.Gly85Glu ABCC7 p.Gly85Glu ABCC7 p.Gly85Glu - Current age and clinical variables in a group of European cystic fibrosis (CF) patients, carrying the G85E mutation and a known second mutation not associated with pancreatic sufficiency (PS), compared to two groups of CF patients not carrying the G85E mutation and having either pancreatic insufficiency (PI) or PS G85E PS PI G85E versus PS Subjects n 55 44 55 Current age yrs 18.2¡9 (2-51) 18.2¡9 (2-52) 18.9¡9 (3-46) 0.06# Age at time of diagnosis months 22 (3-124) 44 (6-169) 6 (2-28) 0.13} Sweat chloride mEq?L-1 106 (95-115) 100 (78-109) 102 (94-110) 0.0018} Presenting symptoms Steatorrhea 40 5 84 0.0001z Failure to thrive 40 14 71 0.0001z Meconium ileus 2 0 12 0.49z Respiratory 78 74 63 0.17z Pancreatic insufficiency 54 0 100 v0.0001z Most recent weight for height percentile 57¡4 72¡5 58¡5 0.02# Most recent FEV1 % pred 69¡5 85¡7 66¡5 0.08# Chronic P. aeruginosa colonisation 42 23 46 0.0083z Complications Liver cirrhosis 9 0 11 v0.05z CF-RD 11 2 13 0.1z DIOS 15 7 9 0.11z Pancreatitis n 2 2 0 0.55z Data are presented as mean¡SD (range), median (interquartile range), mean¡SEM or % unless otherwise stated. Subjects were matched for centre, sex and age. FEV1: forced expiratory volume in one second; pred: predicted; P. aeruginosa: Pseudomonas aeruginosa; CF-RD: cystic fibrosis-related diabetes; DIOS: distal intestinal obstruction syndrome. Statistical analysis by paired t-test# , Wilcoxon signed-ranks test} and Fisher exact testz . Login to comment 124 ABCC7 p.Gly85Glu ABCC7 p.Gly85Glu A+B 0.5 1.5 3.5 0.5 1.5 3.5 0.5 1.5 3.5 Time h G85E V470 G85E M470 WT-CFTR V470 C Fig. 1. Login to comment 125 ABCC7 p.Gly85Glu - Analysis of biogenesis and degradation of G85E-cystic fibrosis transmembrane conductance regulator (CFTR). Login to comment 126 ABCC7 p.Gly85Glu ABCC7 p.Gly85Glu COS cells transfected with either G85E-V470-, G85E-M470- or wild type-V470-CFTR were metabolically labelled and chased for the times indicated. Login to comment 129 ABCC7 p.Gly85Glu has been shown here that the G85E group has more severe disease when considering the same parameters. Login to comment 130 ABCC7 p.Gly85Glu Conversely, there are some differences with classical PI patients: 43% of the G85E patients are PS; and steatorrhea and failure to thrive are less frequent presenting symptoms. Login to comment 136 ABCC7 p.Gly85Glu In the total G85E group studied, the frequency of PI was 57%. Login to comment 137 ABCC7 p.Trp1282* ABCC7 p.Asn1303Lys In patients carrying mutations like F508del, N1303K and W1282X, which correlate with a severe phenotype, w95% have PI [21]. Login to comment 138 ABCC7 p.Arg117His ABCC7 p.Ala455Glu ABCC7 p.Arg334Trp In patients carrying mutations such as R117H, A455E, R334W and 3849z10 kb CwT, which are reported to correlate with a milder phenotype, 40-87% have PS [21, 27]. Login to comment 143 ABCC7 p.Gly85Glu ABCC7 p.Gly85Glu In accordance with this report, the G85E PS patients in the present study are significantly younger than the G85E PI patients. Login to comment 146 ABCC7 p.Gly85Glu Modifying genes can, at present, not yet be studied, but they could explain the rather infrequent occurrence of meconium ileus in the larger group of G85E patients. Login to comment 147 ABCC7 p.Gly85Glu In a previous study, it was found that G85E-CFTR fails to mature and, therefore, is a class II mutation [31]. Login to comment 149 ABCC7 p.Gly85Glu The heterogeneity in disease severity in the group of G85E-CF patients is thus remarkable for a class II mutation, unless if it is conferred by the mutation on the other chromosome. Login to comment 151 ABCC7 p.Gly85Glu However, the haplotype background of G85E-CFTR genes is mostly unknown. Login to comment 152 ABCC7 p.Gly85Glu ABCC7 p.Gly85Glu G85E-CFTR was, therefore, studied both on a M470 and a V470 background, in order to investigate if G85E-CFTR properties are affected by the amino acid found at the M470V position and in this way could explain the observed disease variability. Login to comment 153 ABCC7 p.Gly85Glu ABCC7 p.Gly85Glu Both G85E- M470- and G85E-V470-CFTR, however, completely failed to mature. Login to comment 154 ABCC7 p.Gly85Glu On the basis of the present in vitro findings, as well as on the basis of the clinical findings in the patient group, G85E can be classified as a mutation associated with severe disease. Login to comment 156 ABCC7 p.Gly85Glu Even so, the age at diagnosis was lower in G85E patients, supporting the idea of a more severe phenotype. Login to comment 158 ABCC7 p.Gly85Glu In the present study G85E patients have more severe lung disease as assessed both by more frequent chronic P. aeruginosa infection and worse most recent FEV1 % pred. Login to comment 159 ABCC7 p.Gly85Glu In conclusion, G85E is associated with a severe phenotype. Login to comment 164 ABCC7 p.Gly85Glu European G85E survey contributors: T. Bienvenu (Hoˆpital Cochin, Paris, France); R. Cabanas (Hospital Clinico, Santiago, Spain); T. Casals (Hospital Duran I Reynals, Barcelona, Spain); G. Castaldo (Universita Federico II - Ceinge, Napoli, Italy); C. Castellani (Ospedale Civile Maggiore, Verona, Italy); J. Dapena (Hospital U. Login to comment