clin
Clinics
Clinics
1807-5932
1980-5322
Faculdade de Medicina / USP
São Paulo, SP, Brazil
OBJETIVO: Analisar a freqüência da mutação delta F508 (deltaF508) em 108 pacientes não aparentados, com fibrose cística e comparou os resultados com os dados de outros estudos brasileiros. A fibrose cística (CF) constitui a doença genética mais comum em populações caucasianas, sendo a deltaF508 a mais freqüente dentre as mutações relacionadas à doença. MÉTODO: A freqüência da deltaF508 foi analisada por meio da Reação em Cadeia da Polimerase (PCR) seguida de detecção em géis de poliacrilamida a 8%. RESULTADOS: Vinte e três dos 108 pacientes foram homozigotos para a mutação (21,3%), 50 foram heterozigotos (46,3%) e os 35 restantes não eram portadores da deltaF508 (32,4%). Em termos de alelos, foram observados 96 mutados (44,45%) e 120 do tipo selvagem (55,55%), ou seja, não portadores da mutação. CONCLUSÃO: A freqüência de 44,45% de alelos mutados encontrada no estudo é mais elevada que os 33,0% descritos em pesquisa realizada em São Paulo em 1993, e ligeiramente mais baixa que os 48,0% encontrados em relatos mais recentes. Além disso, nossos resultados corroboraram a idéia de que a freqüência da mutação deltaF508 é mais baixa no Brasil em comparação a países europeus e nos Estados Unidos da América (cerca de 70,0%), provavelmente devido a maior miscigenação racial. Estas observações terão que ser consideradas antes da implementação de testes genéticos de triagem no Brasil.
ORIGINAL RESEARCH
Frequency of the DF508 mutation in 108 cystic fibrosis patients in São Paulo: comparison with reported Brazilian data
Freqüência da mutação DF508 em 108 pacientes com fibrose cística de São Paulo: comparação com dados de estudos brasileiros
Thelma Suely Okay; Wagner Paes Oliveira; Roberto Raiz-Júnior
*
; Joaquim Carlos Rodrigues; Gilda Maria Bárbaro Del Negro
Laboratory of Medical Investigation (LIM/36) of the Department of Paediatrics, Hospital das Clínicas, Faculty of Medicine, University of São Paulo São Paulo/SP, Brazil, and the Pneumology Unit of the Child Institute, Hospital das Clínicas, Faculty of Medicine, University of São Paulo São Paulo/SP, Brazil. E-mail: tsokay@icr.hcnet.usp.br
ABSTRACT
PURPOSE: To analyze the frequency of the delta F508 (DF508) deletion mutation in 108 unrelated cystic fibrosis patients and compare the results with the previously reported data for Brazilian patients. Cystic fibrosis is the leading cause of genetic disease in Caucasians, and the DF508 deletion is the most common mutation associated with the disease.
METHOD: The frequency of the DF508 mutation was assessed by means of a polymerase chain reaction (PCR) followed by detection in 8% silver-stained polyacrylamide gels.
RESULTS: Twenty-three of 108 patients (21.3%) were homozygous for the DF508 deletion, 50 were heterozygous (46.3%), and the remaining 35 (32.4%) were non-carriers. In terms of alleles, there were 96 mutated (96/216 or 44.45%) and 120 wild-type ones (120/216 or 55.5%).
CONCLUSION: The 44.45% of affected alleles that were found is higher than the 33% first described in 1993, but slightly lower than the 48% recently reported. Moreover, our data corroborated the idea that the frequency of the DF508 mutation is lower in Brazil in comparison to that found in studies carried out in Europe and North American (circa 70.0%), probably due to increased racial miscegenation. These findings must be taken into account before any genetic screening of the population is proposed in Brazil.
Keywords: CFTR. DF508. Mutation. Deletion. Cystic fibrosis.
RESUMO
OBJETIVO: Analisar a freqüência da mutação delta F508 (DF508) em 108 pacientes não aparentados, com fibrose cística e comparou os resultados com os dados de outros estudos brasileiros. A fibrose cística (CF) constitui a doença genética mais comum em populações caucasianas, sendo a DF508 a mais freqüente dentre as mutações relacionadas à doença.
MÉTODO: A freqüência da DF508 foi analisada por meio da Reação em Cadeia da Polimerase (PCR) seguida de detecção em géis de poliacrilamida a 8%.
RESULTADOS: Vinte e três dos 108 pacientes foram homozigotos para a mutação (21,3%), 50 foram heterozigotos (46,3%) e os 35 restantes não eram portadores da DF508 (32,4%). Em termos de alelos, foram observados 96 mutados (44,45%) e 120 do tipo selvagem (55,55%), ou seja, não portadores da mutação.
CONCLUSÃO: A freqüência de 44,45% de alelos mutados encontrada no estudo é mais elevada que os 33,0% descritos em pesquisa realizada em São Paulo em 1993, e ligeiramente mais baixa que os 48,0% encontrados em relatos mais recentes. Além disso, nossos resultados corroboraram a idéia de que a freqüência da mutação DF508 é mais baixa no Brasil em comparação a países europeus e nos Estados Unidos da América (cerca de 70,0%), provavelmente devido a maior miscigenação racial. Estas observações terão que ser consideradas antes da implementação de testes genéticos de triagem no Brasil.
Unitermos: CFTR. DF508. Mutação. Deleção. Fibrose cística.
Cystic fibrosis (CF) is the most common potentially lethal autosomal recessive disease of Caucasians. The affected gene, CFTR (cystic fibrosis transmembrane conductance receptor), has been determined to code for a chloride channel. Laboratory diagnosis is based on the finding of abnormally high concentrations of chloride in sweat.1 The clinical features of CF are dominated by involvement of the respiratory tract, where obstruction of the airways by thick, sticky mucus and subsequent infection, especially with Pseudomonas species, predominate. In most patients, there is also involvement of the intestinal tract leading to pancreatic insufficiency as a result of obstruction of the pancreatic ducts and subsequent scarring and destruction of exocrine function.2
The CFTR gene is composed of 250,000 base pairs and 27 exons and encodes a protein of 1,480 amino acids. The finding that one particular mutation, the delta F508 (DF508), which is a 3 base-pair deletion in exon 10 of the CFTR gene corresponding to codon 508 (phenylalanine) of the protein, is responsible for up to 70.0% of all mutations found in CF patients tested so far has made its molecular detection a very attractive diagnostic tool.3 However, it has been shown that the frequency of this mutation varies significantly among ethnic groups, ranging from 26.0% in Turkey to 88.0% in Denmark.4
A few Brazilian studies carried out in the south and southeast regions of Brazil found differences with respect to the frequency of the DF508 mutation among CF patients and also in comparison to those reported in European countries and in the USA.5 In 24 patients in São Paulo, 33.0% of alleles were affected;6 In 17 patients in Rio de Janeiro, a frequency of 35.0% of affected alleles was found.7 In 190 patients from São Paulo, Paraná, and Rio Grande do Sul, 47.0% had the DF508 mutation.8 In another study of 120 chromosomes of 60 patients in São Paulo, a frequency of 31.7% of alleles with the DF508 mutation was found.9 In 61 patients from the South of Brazil, 50.8 % of the alleles had the mutation.10 Of 44 patients from Rio de Janeiro, 47.7% were affected, with a frequency of 30.7% affected alleles11 More recently, among 160 Brazilian patients in a study conducted in São Paulo, 48.4% of alleles were affected,12 and in 77 patients from the south of Brazil, 48.7% of alleles had the DF508 mutation.13 Raskin et al. (2004) concluded that the frequency of the DF508 mutation varies remarkably according to geographic and ethnic origin of patients (Euro-Brazilians or Afro-Brazilians).14
PATIENTS AND METHODS
This study was approved by the Ethics Committee of the Faculty of Medicine, University of São Paulo, Brazil.
One-hundred and eight unrelated clinically and laboratory diagnosed CF patients were enrolled in this study to determine the frequency of DF508-mutated alleles in this population. We aimed at comparing our data with those previously reported with respect to Brazilian CF patients.5-13
Two milliliters of whole blood samples (EDTA, Becton Dickinson) were drawn from patients after informed consent. DNA extraction was performed according to a previously described salting out protocol.15 The presence of the DF508 mutation was determined by means of a classical PCR followed by detection of amplification products in silver-stained polyacrylamide gel electrophoresis according to a previously described protocol,16,17 which was modified to fit our laboratory conditions.
DNA samples of non-carrier subjects (having 2 wild-type alleles) yielded a unique 98 bp (base-pair) fragment, whereas samples from heterozygous patients had 2 amplified fragments, 1 of 98 bp and 1 of 95 bp (lacking 3 base-pairs), and finally DNA from homozygous individuals had only 1 amplified fragment of 95 bp. Amplifications were performed as follows: 10 ng of genomic DNA, 0.4 mM of each of the primers "sense" C16B (5'- GTTTTCCTGGATTATGCCTGGGCA-3' and "anti-sense" C16D (5'- GTTGGCATGCTTTGATGACGTTTC); 1.5 mM of MgCl2 , 2.5 U of Taq DNA polymerase (Amersham-Pharmacia Biotech). After an initial denaturation step of 5 min. at 95°C, 40 cycles of amplification were performed in a Minicycler PT-150, (MJ Research). Cycles consisted of 1 min. at 95°C, 1 min. at 55°C and 1 min. at 72°C, and were followed by a final extension step of 5 min. at 72°C.
Ten microliters of amplification products were analyzed by means of vertical electrophoresis in 8% polyacrylamide gels under non-denaturing conditions for 4 h and 30 min. (25 mA, 450 V, 20 W) in a refrigerated electrophoresis apparatus (Höefer SE 660, Amersham-Pharmacia Biotech). Then, gels were silver-stained, washed, and fixed according a previously described protocol18 and afterwards were dried in a gel dryer (BioRad, USA), at 80°C for 2 h and 30 min.
RESULTS
Among the 108 patients studied, we found 23 (21.3%) homozygous for the DF508 deletion mutation, 50 heterozygous (46.3%), and 35 (32.4%) non-carriers. In terms of alleles, there were 96 mutated (96/216 or 44.45%) and 120 wild-type ones (120/216 or 55.5%).
Table 1 summarizes the data of 14 Brazilian studies performed in cystic fibrosis patients according to the number of alleles studied, the region of the country, and the frequency of DF508-mutated alleles. Briefly, the data show that the totality of reports included south or southeast regions patients, with a great variability of either DF508 mutation frequency as well as other CF-associated mutations (21.0 to 81.0%).
Figure 1 shows the detection of PCR products in 8% polyacrylamide gels. Homozygous patients (ho) have two 95 bp products, indicating 2 alleles with the DF508 mutation; heterozygous ones (he) have one 95 bp product one 98 bp product, indicating one DF508-mutated allele and one non-carrier (wild type) allele; and finally non-affected individuals or non-carriers (nc) have two 98 bp products, indicating 2 non-mutated alleles. The molecular weight marker used is the 25 bp marker from Invitrogen (USA).
DISCUSSION
The frequency of DF508-mutated alleles in the present study was 44.5%. This frequency is higher than the 33.0% and the 35.0% described by Martins et al. (1993)6 and De Miranda et al. (1993)7, respectively, but it is noteworthy that they studied a limited number of patients (24 in São Paulo and 17 in Rio de Janeiro). However, Parizotto et al. (1997)9 studied 120 chromosomes from 60 CF patients of the State of São Paulo and reported that only 31.7% of them had DF508-mutated alleles. Similarly, Cabello et al. (1999) described a frequency of 30.68% of alleles with the DF508 mutation in 88 patients from the State of Rio de Janeiro.11 On the contrary, Raskin et al. (1993)8 studied 190 patients from the south and the southeast of Brazil: 60 from Rio Grande do Sul, 24 from Santa Catarina, 17 from Paraná, 58 from São Paulo and 31 from Minas Gerais. They found an overall frequency of 47.0% of alleles with the DF508 mutation. However, when the frequencies were considered according to the state of origin of patients, they found 49.0% in Rio Grande do Sul, 27.0% in Santa Catarina, 44.0% in Paraná, 52.0% in São Paulo and 53.0% in Minas Gerais. In addition, Bernardino et al. (2000)12 and Streit et al. (2003)13 found higher frequencies of alleles with the DF508 mutation that were very similar (48.4% and 48.7%, respectively), but the former study did not mention whether the patients were all from the State of São Paulo, and the latter was carried out in the State of Rio Grande do Sul, in the south region of Brazil. Raskin et al. in a series of articles that analyzed the frequency of the DF508 mutation as well as other common mutations associated with CF in Brazilian patients19,20,14 initially cited a frequency of 47.0% in Brazilian patients of European origin,19 then a frequency ranging from 30.7 to 50.8%,20 and finally a striking difference in a screening for the 70 most common CF mutations (including DF508) between Euro-Brazilians (75.0%) and Afro-Brazilians (21.0%).14
It is interesting to point out that in all polyacrylamide gels that were performed on heterozygous samples, 2 fragments of molecular weights between 100 bp and 125 bp were present. This phenomenon has already been observed and reported,21 but the relevance of these DNA fragments has still to be investigated. Nevertheless, these spurious fragments act as DNA markers for alleles that are heterozygous for the DF508 mutation.
The present study added 216 chromosomes to the list of 1,652 already investigated in Brazilian CF patients with respect to the DF508 mutation, of which only 284 alleles are certain to belong to patients of the State of São Paulo. The 44.45% of DF508-mutated alleles cited in the present study is within the range of frequencies already reported. Furthermore, all performed Brazilian studies (including ours) tend to indicate a lower frequency of DF508-mutated alleles in Brazil in comparison to European and North American studies (around 70.0%). This is probably due to the higher genetic heterogeneity of our population. These results emphasize the need to re-evaluate the cost vs. benefit ration regarding DNA-based tests for genetic screening in highly heterogeneous populations such as the Brazilian because they will be surely less effective in detecting DF508 mutations as well as in other common CF mutations.
Received for publication on December 02, 2004.
Accepted for publication on January 01, 2005.
*
In memorian
1. Welsh M, Smith AE. Molecular mechanisms of CFTR: chloride channel dysfunction in cystic fibrosis. Cell 1993;73:1251-4.
Molecular mechanisms of CFTR: chloride channel dysfunction in cystic fibrosis
Cell
1993
1251
4
73
Welsh
M
Smith
AE
2. Noone PG, Olivier KN, Knowles MR. Modulation of the ionic milieu of the airway in health and disease. Annu Rev Med 1994;45:421-34.
Modulation of the ionic milieu of the airway in health and disease
Annu Rev Med
1994
421
34
45
Noone
PG
Olivier
KN
Knowles
MR
3. Riordan JR, Rommens JM, Kerem B, Alon N, Rozmahel K, Grzelczak Z, et al. Identification of the cystic fibrosis gene: cloning and characterization of complementary DNA. Science 1989;245:1066-73.
Identification of the cystic fibrosis gene: cloning and characterization of complementary DNA
Science
1989
1066
73
245
Riordan
JR
Rommens
JM
Kerem
B
Alon
N
Rozmahel
K
Grzelczak
Z
4. Tsui LC, Buchwald M. Cystic fibrosis. Ann Med Genet 1992;24:192-245.
Cystic fibrosis
Ann Med Genet
1992
192
245
24
Tsui
LC
Buchwald
M
5. Tsui LC. The spectrum of cystic fibrosis mutations. Trends Genet 1992;8:392-8.
The spectrum of cystic fibrosis mutations
Trends Genet
1992
392
8
8
Tsui
LC
6. Martins CS, Ribeiro F, Costa FF. Frequency of the cystic fibrosis delta F508 mutation in a population from the State of São Paulo, Brazil. Braz J Med Biol Res 1993;26:1037-40.
Frequency of the cystic fibrosis delta F508 mutation in a population from the State of São Paulo, Brazil
Braz J Med Biol Res
1993
1037
40
26
Martins
CS
Ribeiro
F
Costa
FF
7. De Miranda AB, Llerena Júnior J, Dallalana LT, Moura-Neto RS, Suffys PN, Degrave WM. Use of PCR for the determination of the frequency of the delta F508 mutation in Brazilian cystic fibrosis patients. Mem Inst Oswaldo Cruz 1993;88:309-12.
Use of PCR for the determination of the frequency of the delta F508 mutation in Brazilian cystic fibrosis patients
Mem Inst Oswaldo Cruz
1993
309
12
88
De Miranda
AB
Llerena Júnior
J
Dallalana
LT
Moura-Neto
RS
Suffys
PN
Degrave
WM
8. Raskin S, Philllips JA, Krishnamani MR, Unencak-Jones C, Parker RA, Dewsen E, et al. Regional distribution of cystic fibrosis-linked DNA haplotypes in Brazil: Multicenter Study. Hum Biol 1997;69:75-88.
Regional distribution of cystic fibrosis-linked DNA haplotypes in Brazil: Multicenter Study
Hum Biol
1997
75
88
69
Raskin
S
Philllips
JA
Krishnamani
MR
Unencak-Jones
C
Parker
RA
Dewsen
E
9. Parizotto EA, Bertuzzo CS, Ribeiro AF. Molecular characterization of cystic fibrosis patients in the state of São Paulo. J Med Genet 1997;34:877-81.
Molecular characterization of cystic fibrosis patients in the state of São Paulo
J Med Genet
1997
877
81
34
Parizotto
EA
Bertuzzo
CS
Ribeiro
AF
10. Maróstica PJ, Raskin S & Abreu-e-Silva FA. Analysis of the delta F508 mutation in a Brazilian cystic fibrosis population: comparison of pulmonary status of homozygotes with other patients. Braz J Med Biol Res 1998;31:529-32.
Analysis of the delta F508 mutation in a Brazilian cystic fibrosis population: comparison of pulmonary status of homozygotes with other patients
Braz J Med Biol Res
1998
529
32
31
Maróstica
PJ
Raskin
S
Abreu-e-Silva
FA
11. Cabello GM, Moreira AF, Horovitz D, Correia P, Santa Rosa A, Llerena Jr, et al. Cystic fibrosis: low frequency of DF508 mutation in 2 population samples from Rio de Janeiro, Brazil. Hum Biol 1999;71:189-96.
Cystic fibrosis: low frequency of DF508 mutation in 2 population samples from Rio de Janeiro, Brazil
Hum Biol
1999
189
96
71
Cabello
GM
Moreira
AF
Horovitz
D
Correia
P
Santa Rosa
A
Llerena
Jr
12. Bernardino AL, Ferri A, Passos-Bueno MR, KIM CE, Nakaie CM, Gomes CE, et al. Molecular analysis in Brazilian cystic fibrosis patients reveals five novel mutations. Genet Test 2000;4:69-74.
Molecular analysis in Brazilian cystic fibrosis patients reveals five novel mutations
Genet Test
2000
69
74
4
Bernardino
AL
Ferri
A
Passos-Bueno
MR
KIM
CE
Nakaie
CM
Gomes
CE
13. Streit C, Burlamaque-Neto AC, De Abreu e Silva F, Giugliani R, Saraiva Pereira ML. CFTR gene: molecular analysis in patients from the South Brazil. Mol Genet Metabol 2003;78:259-64.
CFTR gene: molecular analysis in patients from the South Brazil
Mol Genet Metabol
2003
259
64
78
Streit
C
Burlamaque-Neto
AC
De Abreu e Silva
F
Giugliani
R
Saraiva Pereira
ML
14. Raskin S, Pereira L, Reis F, Rosario NA, Ludwig N, Valentim L, et al. High allelic heterogeneity between Afro-Brazilians and Euro-Brazilians impacts cystic fibrosis genetic testing. Genetic Testing 2003;7(3):213-8.
High allelic heterogeneity between Afro-Brazilians and Euro-Brazilians impacts cystic fibrosis genetic testing
Genetic Testing
2003
213
8
3
7
Raskin
S
Pereira
L
Reis
F
Rosario
NA
Ludwig
N
Valentim
L
15. Miller AS, Dykes DD, Polesky HF. A simple salting out procedure for extracting DNA from human nucleated cells. Nucleic Acids Res 1988;16:1215.
A simple salting out procedure for extracting DNA from human nucleated cells
Nucleic Acids Res
1988
1215
16
Miller
AS
Dykes
DD
Polesky
HF
16. Saiki Rk, Scharf S, Faloona F, Mullis Kb, Horn Gt, Erlich HA, et al. Enzymatic amplification of beta-globin genomic sequences and restriction site analysis for diagnosis of sickle cell anemia. Science 1985;230:1350-54.
Enzymatic amplification of beta-globin genomic sequences and restriction site analysis for diagnosis of sickle cell anemia
Science
1985
1350
54
230
Saiki
Rk
Scharf
S
Faloona
F
Mullis
Kb
Horn
Gt
Erlich
HA
17. Saiki RK, Gelfand DH, Stoffel S, Scharf SJ, Higuchi R, Horn GT, et al. Primer-directed enzymatic amplification of DNA with a thermostable DNA polymerase. Science 1988;239:487-91.
Primer-directed enzymatic amplification of DNA with a thermostable DNA polymerase
Science
1988
487
91
239
Saiki
RK
Gelfand
DH
Stoffel
S
Scharf
SJ
Higuchi
R
Horn
GT
18. Bassam BJ, Caetano-Anollés G, Gresshoff PM. Fast and sensitive silver staining of DNA in polyacrylamide gels. Anal Biochem 1991;196:80-3.
Fast and sensitive silver staining of DNA in polyacrylamide gels
Anal Biochem
1991
80
3
196
Bassam
BJ
Caetano-Anollés
G
Gresshoff
PM
19. Raskin S, Phillips JA, Kaplan G, McClure M, Vnencak-Jones C, Rozov T, et al. Geographic heterogeneity of 4 common worldwide cystic fibrosis non-DF508 mutations in Brazil. Hum Biol 1999;71(1):111-121.
Geographic heterogeneity of 4 common worldwide cystic fibrosis non-DF508 mutations in Brazil
Hum Biol
1999
111
121
1
71
Raskin
S
Phillips
JA
Kaplan
G
McClure
M
Vnencak-Jones
C
Rozov
T
20. Goloni-Bertollo EM, Rossit AR, Junior JB, Fett-Conte AC, Raskin S. CFTR molecular analysis reveals infrequent allele frequencies in nine cystic fibrosis patients from São Paulo State, Brazil. Hum Biol 2003; 75(3):393-8.
CFTR molecular analysis reveals infrequent allele frequencies in nine cystic fibrosis patients from São Paulo State, Brazil
Hum Biol
2003
393
8
3
75
Goloni-Bertollo
EM
Rossit
AR
Junior
JB
Fett-Conte
AC
Raskin
S
21. Chong GL, Thibodeau SN. A simple assay for the screening of the cystic fibrosis allele in carriers of the Phe508 deletion mutation. Mayo Clin Proc 1990;65:1072-6.
A simple assay for the screening of the cystic fibrosis allele in carriers of the Phe508 deletion mutation
Mayo Clin Proc
1990
1072
6
65
Chong
GL
Thibodeau
SN
Autoria
Thelma Suely Okay
Universidade de São Paulo, Faculty of Medicine , Hospital das Clínicas, São Paulo, São Paulo, BrazilUniversidade de São PauloBrazilSão Paulo, São Paulo, BrazilUniversidade de São Paulo, Faculty of Medicine , Hospital das Clínicas, São Paulo, São Paulo, Brazil
Universidade de São Paulo, Faculty of Medicine , Hospital das Clínicas, São Paulo, São Paulo, BrazilUniversidade de São PauloBrazilSão Paulo, São Paulo, BrazilUniversidade de São Paulo, Faculty of Medicine , Hospital das Clínicas, São Paulo, São Paulo, Brazil
Wagner Paes Oliveira
Universidade de São Paulo, Faculty of Medicine , Hospital das Clínicas, São Paulo, São Paulo, BrazilUniversidade de São PauloBrazilSão Paulo, São Paulo, BrazilUniversidade de São Paulo, Faculty of Medicine , Hospital das Clínicas, São Paulo, São Paulo, Brazil
Universidade de São Paulo, Faculty of Medicine , Hospital das Clínicas, São Paulo, São Paulo, BrazilUniversidade de São PauloBrazilSão Paulo, São Paulo, BrazilUniversidade de São Paulo, Faculty of Medicine , Hospital das Clínicas, São Paulo, São Paulo, Brazil
Roberto Raiz-Júnior
Universidade de São Paulo, Faculty of Medicine , Hospital das Clínicas, São Paulo, São Paulo, BrazilUniversidade de São PauloBrazilSão Paulo, São Paulo, BrazilUniversidade de São Paulo, Faculty of Medicine , Hospital das Clínicas, São Paulo, São Paulo, Brazil
Universidade de São Paulo, Faculty of Medicine , Hospital das Clínicas, São Paulo, São Paulo, BrazilUniversidade de São PauloBrazilSão Paulo, São Paulo, BrazilUniversidade de São Paulo, Faculty of Medicine , Hospital das Clínicas, São Paulo, São Paulo, Brazil
Joaquim Carlos Rodrigues
Universidade de São Paulo, Faculty of Medicine , Hospital das Clínicas, São Paulo, São Paulo, BrazilUniversidade de São PauloBrazilSão Paulo, São Paulo, BrazilUniversidade de São Paulo, Faculty of Medicine , Hospital das Clínicas, São Paulo, São Paulo, Brazil
Universidade de São Paulo, Faculty of Medicine , Hospital das Clínicas, São Paulo, São Paulo, BrazilUniversidade de São PauloBrazilSão Paulo, São Paulo, BrazilUniversidade de São Paulo, Faculty of Medicine , Hospital das Clínicas, São Paulo, São Paulo, Brazil
Gilda Maria Bárbaro Del Negro
Universidade de São Paulo, Faculty of Medicine , Hospital das Clínicas, São Paulo, São Paulo, BrazilUniversidade de São PauloBrazilSão Paulo, São Paulo, BrazilUniversidade de São Paulo, Faculty of Medicine , Hospital das Clínicas, São Paulo, São Paulo, Brazil
Universidade de São Paulo, Faculty of Medicine , Hospital das Clínicas, São Paulo, São Paulo, BrazilUniversidade de São PauloBrazilSão Paulo, São Paulo, BrazilUniversidade de São Paulo, Faculty of Medicine , Hospital das Clínicas, São Paulo, São Paulo, Brazil
SCIMAGO INSTITUTIONS RANKINGS
Universidade de São Paulo, Faculty of Medicine , Hospital das Clínicas, São Paulo, São Paulo, BrazilUniversidade de São PauloBrazilSão Paulo, São Paulo, BrazilUniversidade de São Paulo, Faculty of Medicine , Hospital das Clínicas, São Paulo, São Paulo, Brazil
Universidade de São Paulo, Faculty of Medicine , Hospital das Clínicas, São Paulo, São Paulo, BrazilUniversidade de São PauloBrazilSão Paulo, São Paulo, BrazilUniversidade de São Paulo, Faculty of Medicine , Hospital das Clínicas, São Paulo, São Paulo, Brazil
Okay, Thelma Suely et al. Freqüência da mutação deltaF508 em 108 pacientes com fibrose cística de São Paulo: comparação com dados de estudos brasileiros. Clinics [online]. 2005, v. 60, n. 2 [Acessado 18 Abril 2025], pp. 131-134. Disponível em: <https://doi.org/10.1590/S1807-59322005000200009>. Epub 26 Abr 2005. ISSN 1980-5322. https://doi.org/10.1590/S1807-59322005000200009.
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