ABCMdb

PMID: 1715308

Dork T, Wulbrand U, Richter T, Neumann T, Wolfes H, Wulf B, Maass G, Tummler B
Cystic fibrosis with three mutations in the cystic fibrosis transmembrane conductance regulator gene.
Hum Genet. 1991 Aug;87(4):441-6., [PubMed]

Sentences

No. Mutations Sentence Comment

2 ABCC7 p.Arg553Gln The R553Q mutation was found on the maternal AF508-CFTR gene. Login to comment 4 ABCC7 p.Arg553Gln Other members of this protein superfamily contain a glutamine instead of arginine at the homologous position, suggesting a modulating rather than disease-causing role of the R553Q mutation in CFTR. Login to comment 5 ABCC7 p.Arg553Gln The amplification refractory mutation system did not detect the R553Q mutation in a further 65 normal, 113 AF508, and 91 non-AF508 CF chromosomes. Login to comment 6 ABCC7 p.Arg553* The index case carried the R553X nonsense mutation on the paternal chromosome. Login to comment 7 ABCC7 p.Arg553* The R553X mutation was present on a further 9 out of 86 German non-AF508 CF chromosomes linked with the XV2c-KM19- Mp6d9-J44-GATT haplotypes 2-2-2-1-1 and 1-1-2-1-2. Login to comment 8 ABCC7 p.Arg553* ABCC7 p.Arg553* The location of R553X on separate haplotypes including both alleles of the intragenic GATT repeat suggests an ancient and/or multiple origins of the R553X mutations. Login to comment 9 ABCC7 p.Arg553* ABCC7 p.Arg553* ABCC7 p.Arg553Gln The association of the genotype of the CFTR mutation and the clinical phenotype was assessed for the patients carrying the related genotypes AF508/AF508 (n = 80), AF508/R553X (n = 9) and AF508-R553Q/R553X (n = 1). Login to comment 31 ABCC7 p.Arg553* For analysis of the R553X mutation, exon 11 of CFTR was amplified from genomic DNA by PCR using the flanking intron primers 11i-5 5'-CAACTGTGGTTAAAGCAATAGTGT-3' and 11i-3 5'-GCACAGATTCTGAGTAACCATAAT-3' (Cutting et al. 1990) (35 cycles, 90s at 52~ 60s at 72~ 60s at 91~ The 425-bp DNA fragment was either digested with HincII or MboI and subsequently separated by agarose gel electrophoresis. Login to comment 32 ABCC7 p.Arg553Gln ABCC7 p.Arg553Gln The R553Q mutation was detected by the amplification refractory mutation system (ARMS) (Newton et al. 1989) using the flanking intron primer 11i-5 as the common primer, and the primer sequences 5'- CACCTTGCTAAAGAAATTCTTCCTC-3' for the normal allele and 5'-CACCTTGCTAAAGAAATI'CTTCCTC-3'for the R553Q allele (35 cycles of PCR, 30 s at 62~ 45 s at 72~ 90 s at 91~ 214-bp product). Login to comment 34 ABCC7 p.Arg553* ABCC7 p.Arg553Gln The presence of the R553X and R553Q mutations was verified by direct genomic sequencing of the PCR product (Gyllenstein and Erlich 1988). Login to comment 41 ABCC7 p.Gly551Asp ABCC7 p.Arg553* ABCC7 p.Arg553* Results and discussion Incidence and haplotype of the R553X mutation Seventy-five German CF families with at least one non-AF508 CF chromosome were screened for the G551D and R553X mutations in exon 11 of CFTR using MboI or HincII digestions (Cutting et al. 1990). Login to comment 44 ABCC7 p.Arg553* These data indicate that the R553X nonsense mutation, discovered in two American Black CF patients (Cutting et al. 1990) accounts for approximately 10% of mutations on German non-AF508 CF chromosomes. Login to comment 46 ABCC7 p.Arg553* We found the R553X mutation on chromosomes with the XV2cT/KM19P/Mp6d9/J44/GATT haplotype 2-2-21-1 (one case) and 1-1-2-1-2 (others). Login to comment 47 ABCC7 p.Arg553* In American Blacks, the R553X mutation was detected on the XV2cT/KM19P/Mp6d-9 marker haplotype 2-2-2 (Cutting et al. 1990). Login to comment 49 ABCC7 p.Arg553* These findings suggest an ancient and/or multiple origins of the R553X mutations. Login to comment 50 ABCC7 p.Arg553* ABCC7 p.Arg553Gln The R553Q mutation In one patient who was harboring the R553X mutation, another nucleotide change was detected at the same codon of CFTR (Fig. 1). Login to comment 51 ABCC7 p.Arg553Gln ABCC7 p.Arg553Gln Guanine 1790 was substituted by an adenine, changing arginine 553 to a glutamine (R553Q). Login to comment 52 ABCC7 p.Arg553* ABCC7 p.Arg553Gln Sequence analysis of the parental samples revealed that the R553Q mutation was present on the maternal AF508 CF chromosome, whereas the paternal chromosome carried the R553X mutation. Login to comment 53 ABCC7 p.Arg553* ABCC7 p.Arg553Gln Hence, the patient with the AF508-R553Q/R553X mutations is the first known CF patient to have inherited three sequence alterations compared with the wild-type CFTR sequence. Login to comment 54 ABCC7 p.Arg553Gln The AF508-R553Q allele was found to carry the haplotype 1-1-2-1-2-2-1-1-1-2 for the polymorphic marker loci " J3.11 (MspI)-J3.11 (TaqI)-GATT-J44-D9-KM19-XV2c- metH (MspI)-metH (TaqI)-metD (TaqI). Login to comment 55 ABCC7 p.Arg553* ABCC7 p.Arg553* ABCC7 p.Arg553Gln The location of Gln553 on this typical AF508-1inked haplotype sugA A C G Contro[ R553X R553X/R553Q _,,,,i-- 1789C-T w, 790 G-A Fig. 1. Login to comment 56 ABCC7 p.Arg553* Direct genomic sequencing of exon 11 of CFFR from a normal subject (left), a carrier for the R553X nonsense mutation (middle) and the index case with mutations at codon 553 on each CF chromosome showing a C---~Tnucleotide substitution at position 1789 (middle, right) and a G---~Asubstitution at position 1790 (righO(arrows) 21l,Bp ARMS-M 214Bp ARMS-N Fig.2. Login to comment 57 ABCC7 p.Arg553Gln ARMS analysisof the inheritanceof the R553Q mutation in a CF family. Login to comment 61 ABCC7 p.Arg553Gln ARMS-M mutant product;ARMS-N normalproduct gests the origin of the R553Q mutation to be a AF508-CFTR gene. Login to comment 62 ABCC7 p.Arg553Gln In order to test this hypothesis, our panel of N and CF chromosomes was screened for the presence of the R553Q mutation. Login to comment 63 ABCC7 p.Gly551Asp ABCC7 p.Arg553* ABCC7 p.Arg553Gln ABCC7 p.Arg553Gln Since R553Q is nested in a duster of other CF mutations, such as G551D and R553X (Cutting et al. 1990), ARMS (Newton et al. 1989) was applied for the specific detection of the R553Q mutation (Fig. 2). Login to comment 64 ABCC7 p.Arg553Gln Using allele-specific primers and the 11i-5 downstream flanking intron primer for amplification of genomic DNA by PCR, the R553Q mutation was not detected on a further 65 normal, 113 AF508 CF and 91 non-AF508 CF chromosomes. Login to comment 65 ABCC7 p.Arg553Gln Hence, the substitution of arginine 553 by glutamine is an infrequent sequence alteration in CFTR. Login to comment 78 ABCC7 p.Arg553* ABCC7 p.Arg553Gln The index case of genotype AF508-R553Q/R553X displays an unusual combination of almost normal sweat test values and severe clinical disease. Login to comment 80 ABCC7 p.Arg553* ABCC7 p.Arg553* ABCC7 p.Arg553Gln In order to assess the severity of CF disease in quantitative terms, the clinical features of the index case AF508-R553Q/R553X were compared with those of patients who carry the related genotypes of CFTR mutations, AF508/AF508 or AF508/ R553X (Table 1). Login to comment 82 ABCC7 p.Arg553* The two groups AF508/AF508 and AF508/R553X with similar distributions for date of birth and age at diagnosis, exhibited comparably severe pulmonary disease as indicated by lung function parameters and alterations in the chest X-ray (Table 1). Login to comment 87 ABCC7 p.Arg553* On the contrary, the genotype AF508/R553X was associated with marked growth retardation, despite the fact that severe symptoms of pancreatic insufficiency had never been observed in any patient. Login to comment 89 ABCC7 p.Arg553* Hence, compound heterozygosity for AF508/R553X seems to lead to a more severe course of CF than homozygosity for the F508 deletion. Login to comment 91 ABCC7 p.Arg553* ABCC7 p.Arg553Gln The comparison of the three genotypes suggests that the nonsense mutation R553X rather than AF508 or AF508-R553Q is associated with retardation of growth and development in the compound heterozygotes. Login to comment 95 ABCC7 p.Arg553* ABCC7 p.Arg553* ABCC7 p.Arg553Gln Anthropometricdata and score refer to the patients' last visit to the CF Clinic (3/90-9/90) AF508/AF508 AF508/R553X AF508-R553Q/R553X Median Range (n = 80) Median Range (n = 9) (singlecase) Age 14.1 2.8-31.5 13.9 7.2-18.1 12.0 Age at diagnosis (years) 0.5 0 - 4.6 0.8 0.13.8 6.9 Sweat test (mmol chloride/I)a 109 78-160 86 80-109 63 Height percentile 48 199 14 740 10 Weight percentile 29 197 8 228 15 Chrispin Norman score of chest X-ray 9 032 11 520 9 Lung function parametersb FEV1 (% predicted) 73 18-114 (n = 65) 64 44-102 75 VC (% predicted) 84 33-118 (n = 65) 78 57-102 85 a Mean value of at least three independent pilocarpine iontophoresis sweat tests b Average values of the forced expiratoryvolume in 1 s (FEV1) and of the forced vital capacity (VC) of the last five pulmonary function tests excluding episodes of airway infections (Rich et al. 1990; Drumm et al. 1990). Login to comment 99 ABCC7 p.Arg553* A significantly lower median value of 86 mmol CI/I was determined for the patient group with compound heterozygosity AF508/ R553X (Table 1). Login to comment 101 ABCC7 p.Arg553Gln The disease-causing mutations in CFTR are obligatorily associated with the defect in chloride transport; hence, the almost normal sweat chloride concentration in this patient suggests that the substitution of arginine 553 by glutamine neither is a neutral polymorphism nor does it cause disease, but rather it modulates the function and/or processing of the AF508-CFTR gene product. Login to comment 107 ABCC7 p.Gly551Asp ABCC7 p.Ala559Thr Interestingly, the disease-causing missense mutations in this region of CFTR, S549(N,I,R), G551D, and A559T (Cutting et al. 1990; Kerem et al. 1990) all affect conserved residues in this consensus sequence, indicating that the amino acids at positions 2, 4, and 12 are essential for the function and/or processing of the CFTR protein. Login to comment 111 ABCC7 p.Arg553Gln The R553Q mutation that we have discovered in our CF patient with borderline sweat tests abolishes this charge and slightly decreases the polarity of the predicted loop 3. Login to comment 119 ABCC7 p.Arg553Gln Hence, if both loops provide essential contacts for promoting channel-mediated chloride transport, it is reasonable to assume that the substitution of arginine 553 by glutamine may partly compensate for the deleterious effect of the omission of phenylalanine 508 of CFTR with respect to anion permeability of the apical membrane of epithelia. Login to comment