Human Reproduction, Vol. 16, No. 10, 2093-2097,
October 2001
© 2001 European Society of Human Reproduction and Embryology
Cystic fibrosis phenotype evaluation and paternity outcome in 50 males with congenital bilateral absence of vas deferens
1 Adult Cystic Fibrosis Care Centre, Centre Hospitalier Lyon-Sud, Pierre-Bénite Cédex, 2 Laboratoire de Biochimie Endocrinienne et Moléculaire, Hôpital Debrousse, Lyon Cédex, 3 Institut Rhonalpin pour l'étude de la reproduction, Bron, 4 Fédération d'Endocrinologie, Hôpital de L'Antiquaille and 5 Service de génétique, Hôtel-Dieu, Lyon, France
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Abstract |
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BACKGROUND: Most infertile males with congenital bilateral absence of vas deferens (CBAVD) carry mutations on the cystic fibrosis transmembrane conductance regulator gene and may express mild cystic fibrosis (CF) symptoms. Barriers to paternity for these men can now be overcome by assisted reproduction. Our aims were to investigate the CF-related phenotype and clinical outcome for 50 patients with CBAVD seen at a CF adult centre between 1992 and 1999. METHODS AND RESULTS: The investigation of the patients included screening for 22 CF mutations and identification of the poly-T variant of intron 8, sweat testing, clinical investigation for CF-related extra-genital manifestations, and genetic counselling. CFTR mutations were detected on 56 alleles of the 50 patients. A total of 15 (30%) was compound heterozygote and 26 (52%) heterozygote. In all, 38% of the patients had a positive sweat test. Four patients were diagnosed with typical CF not detected previously. Twenty-one patients became fathers following ICSI (eight cases), artificial insemination by donor or IVF with sperm donor (seven cases) or through adoption (six cases). A mail survey allowed the identification of CF-related clinical symptoms. Information on the occurrence of CF-related symptoms was obtained for 58.5% of patients: in the absence of initial symptoms, no new clinical signs were reported. CONCLUSION: Patients diagnosed with CBAVD need genetic counselling before assisted reproduction. Even when no wish for paternity is expressed, CF gene screening should be associated with at least a sweat test and clinical evaluation because of possible mild forms of CF disease. Medical follow-up did not reveal any new symptoms.
Key words: congenital bilateral absence of vas deferens/cystic fibrosis/outcome of paternity
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Introduction |
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Congenital bilateral absence of vas deferens (CBAVD) is encountered in 1–2% of infertile males and in most males presenting with cystic fibrosis (CF). Since 1990, CBAVD has been associated with mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene (Dumur et al., 1990
; Anguiano et al., 1992; Chillon et al., 1995). In a review of 420 CBAVD cases, 19% carried two allele mutations, 47% a single mutation, and 34% no identified mutation (Lissens et al., 1996). The presence of subclinical CF symptoms, which include elevated sweat chloride concentrations and sinusitis, has been reported, supporting the concept of incomplete forms of CF (Durieu et al., 1995; Dohle et al., 1999). Since the first description of a pregnancy observed in a couple with a male presenting with CBAVD (Silber et al., 1987), the use of microsurgical or percutaneous epididymal sperm aspiration and ICSI has allowed a significant improvement of the rate of successful pregnancies. Consequently, genetic counselling is advisable. The aims of our retrospective study were to investigate CF-related phenotype and clinical outcome in a cohort of 50 males with CBAVD, as well as to determine the issue of pregnancies for couples after genetic counselling.
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Materials and methods |
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Patients
Fifty patients with CBAVD were investigated between December 1992 and December 1999. Diagnosis criteria for CBAVD as well as clinical, biological and radiological investigations for CF phenotype have been described previously for the first 14 patients (Durieu et al., 1995
). Diagnosis of CBAVD was established on azoospermia in subjects with normal or small sized testes, non-palpable vas deferens, and changes in the physical and biochemical properties of ejaculate (small volume, low pH and low fructose concentration). Absence of infectious events and normal endocrine testicular function were checked for. No patient with renal abnormality was included. Medical history was recorded by the same physician regarding all familial and personal events of medical significance, particularly deaths in childhood, infertility in siblings, symptoms involving respiratory, gastrointestinal and hepatobiliary systems. Sweat testing was performed in all patients using the Gibson and Cooke pilocarpine iontophoresis method (Gibson and Cooke, 1959) in a well-established laboratory. The test was considered positive when the sweat chloride concentration was >60 mmol/l for a sweat collection weight >100 mg.
Analysis of CF gene mutations was made by extracting leukocyte genomic DNA from blood samples collected in ethylenediaminetetra-acetic acid. Leukocytes samples were analysed for a series of 22 CF mutations including the five most frequently encountered in our region (The CF Genotype Consortium, 1994): 
F508, G542X, N1303K, 1717-G—A, 885E; and 17 others: R117H, R334W, R347H, R347P, 556delA, S549N, S549I, S549R, G551D, R553X, R560T, G1244E, S1255X, W1282X, R1283K, 3898ins C, D1270N. The identification of the poly-T variant of intron 8 was also tested in stored specimens.
Biological data recorded included liver function tests, serum pancreatic enzymes (amylasaemia, lipasaemia, trypsinaemia), total cholesterol, fat-soluble vitamins, glucose serum concentration, and glycosylated haemoglobin. All patients had chest roentgenograms, pulmonary function tests, computerized tomographic scan of paranasal sinuses and abdominal ultrasonography.
Genetic counselling was proposed to all couples, including genotype analysis of CFTR mutations for the spouse and geneticist consultation for the couple.
Survey of CF-related clinical symptoms and paternity outcome
Information on medical assisted reproduction techniques was obtained in January 2000, from the andrologist in charge of each patient. Accurate oral information on CF clinical symptoms and genetic counselling was provided to each patient at the first evaluation. A mail investigation carried out throughout 1999 for the 41 patients seen between December 1992 and April 1998 allowed registration of any sign suggesting CF-related non-genital manifestations such as bronchial or sinus infections, gastrointestinal symptoms or any other relevant medical event.
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Results |
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Cohort description and CF criteria
Median age at first consultation for the 50 patients was 33 years (24–54 years). Medical familial investigation found: a CF history in four patients, early infant deaths in the families of two patients, infertility in siblings in six patients.
sCFTR mutation was detected in 56 alleles of the 50 patients: F508 in 30 alleles, R117H in six, D1270N in two, G542X in one, 1717+G-A in one, 2789+5G-A in one, R347H in one and the 5T allele in 14. Fifteen patients (30%) were compound heterozygote, 26 patients (52%) had only one CF mutation and nine (18%) had no CF mutation detected (Table I).
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Sweat chloride concentrations (SCC) were >60 mmol/l in 19 patients (38%) and between 30 and 60 mmol/l in 24 (48%) (Table I
). Thirty patients (60%) had either a positive sweat test (>60 mmol/l) or two CFTR mutations. Twenty-six patients (52%) had computed tomographic scan sinuses anomalies corresponding to polyposis or maxillar sinusitis.
Four cases, not detected previously, were diagnosed as `classical' CF in view of clinical signs suggesting CF as proposed by Stern (Stern et al., 1982): two patients (numbers 5 and 17 in Table I) with CF genotype F508/5T and F508/- respectively had repeated bronchial infections, colonization of sputum with haemophilus influenzae and staphylococcus aureus, reduced forced expiratory volume in one second (FEV1) (60% of predicted value) and positive sweat test (90 mmol/l); the two other patients with one CFTR mutation (D1270N) in number 36 and 5T/5T CFTR genotype for number 15 had positive sweat test (103 and 77 mmol/l respectively) and significantly elevated pancreatic enzymes (two-fold normal values) without steatorrhoea, but with diabetes mellitus in one case.
One patient had asthma since infancy and a negative sweat test, another patient had chronic cough but severe tobacco addiction; two patients had asymptomatic gallstones; and all patients had normal liver function tests.
Paternity outcome
Results are summarized in Table II. Among the 50 CBAVD men, 28 underwent at least one ICSI procedure and three others are in progress (62%). ICSI led to successful pregnancies with live births in eight cases, including two twin pregnancies (10 newborns). Following ICSI failures in 20 cases, six couples underwent IVF with sperm donors (IVFSD) resulting in two successful pregnancies and live births and four failures. Two couples adopted a child after unsuccessful ICSI; for one of them ICSI was attempted in 1991, before any clinical evaluation or genetic counselling. The existence of a F508 mutation in one woman led the couple to choose adoption rather than another ICSI attempt.
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Five couples underwent artificial insemination by donor (AID) as the first procedure, leading to successful pregnancies and live births in all cases. In two cases,
F508 heterozygote mutation was found in the women. Donors underwent a screening for the most common CFTR mutations.
Four couples chose adoption without any attempt at assisted reproduction: one case was motivated by F508 heterozygote mutation in the woman; another case by the age and hormonal status of the woman, and two remaining cases for personal reasons.
Ten men did not undergo any procedure for paternity and for one of them this decision was motivated by CF mutation in his spouse.
In total, 21 men (42%) became fathers, following ICSI procedures in eight cases, AID in five cases, IVFSD in two, and through adoption for six of them (Table II).
Mail survey for CF criteria
Information was obtained for 24 patients of the 41 patients included in the survey (58.5%) with a median follow-up period of 2.8 years (range 0.5–5 years). Bronchial infections only concerned patients with initial respiratory symptoms. Three patients reported symptomatic sinusitis. No patient reported signs suggesting digestive or pancreatic involvement, nor onset of diabetes mellitus.
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Discussion |
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In this cohort of 50 men with CBAVD, screening for 22 CF mutations and testing for the poly-T variant of intron 8 led to the identification of mutation in 56% of alleles. A total of 30% of patients were compound heterozygotes, and 52% were heterozygotes. These results are quite similar to those reported in other publications using limited CFTR gene exon-screening (Chillon et al., 1995
; Lissens et al., 1996; Phillipson et al., 2000). A recent study showed a higher frequency by 6% of detected mutations using extensive screening of all exons as compared with routine screening (Mak et al., 1999). But despite extensive screening, 18 men out of 64 (28%) had no CFTR mutation detected (Mak et al., 1999). Using our procedure that includes screening of 22 CFTR mutations, testing of the 5T variant of intron 8, sweat tests and clinical evaluation, nine patients out of 50 (18%) had neither a positive sweat test, nor any CFTR mutation. Two patients with only one CFTR mutation (2789+5G-A or 5T) had very high SCC (90 and 100 mmol/l). Moreover, clinical investigation led to the diagnosis of symptomatic CF disease with pulmonary or pancreatic manifestations in four patients (8%) not detected previously. It has recently been proposed to lower the upper limit for normal sweat chloride concentrations in infants to 30 mmol/l instead of 60 mmol/l (Farell et al., 2000). This measure is probably relevant for non-classical CF phenotype. In our cohort, 24 (48%) CBAVD men had intermediate values of SCC and only seven (14%) had low SCC values. Therefore, we suggest that sweat testing and clinical investigation should be included in the initial evaluation of CBAVD because there is the possibility of elevated SCC without CF genotype or undiagnosed cases of CF disease who will thereafter need follow-up at a CF care management centre (Mahadeva et al., 1998). Information on the occurrence of clinical symptoms were obtained for only 24 patients (48% of our cohort). Among those for whom this information was available, no new clinical events were reported. It is unlikely that any significant symptoms were missed since extensive information about CF-related disease was given during clinical evaluation and genetic counselling, and most patients had a long follow-up with an andrologist for assisted reproduction treatment.
In our cohort of CBAVD, the rate of paternity after a median follow-up period of 2.8 years is 42%, which is lower than in other reports concerning ICSI outcomes (Phillipson et al., 2000). Several explanations could account for this result: (i) the recruitment of our patients did not depend on their motivation for assisted reproduction since ten patients (22%) did not undergo any procedure for paternity; (ii) the identification of a F508 mutation in four women led to giving up ICSI; (iii) the follow-up period is probably not sufficient since some ICSI procedures are in progress. Twenty one patients achieved paternity: through ICSI for eight patients, sperm donor (AID or IVFSD) for seven patients and adoption for the remaining six.
In conclusion, in our cohort of men presenting with CBAVD, 42% became fathers using various procedures. When no initial symptoms were registered, a short median follow-up period of 2.8 years did not reveal any new clinical signs. Diagnosis of CBAVD requires genetic counselling before proceeding to assisted reproduction. Even in cases without any demand for assisted reproduction, CF gene screening should be associated with sweat testing and an initial thorough clinical evaluation because of possible mild forms of CF disease.
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Notes |
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6 To whom correspondence should be addressed at: Adult Cystic Fibrosis Care Centre, Department of Internal Medicine, Pavillon 1K, Centre Hospitalier Lyon-Sud, 69495 Pierre-Bénite Cédex, France. E-mail: isabelle.durieu{at}chu-lyon.fr
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References |
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Anguiano, A., Oates, R.D., Amos, J.A. et al. (1992) Congenital bilateral absence of vas deferens. A primarily genital form of cystic fibrosis. J. Am. Med. Assoc., 267, 1794–1797.
Chillon, M., Casals, T., Mercier, B. et al. (1995) Mutations in the cystic fibrosis gene in patients with congenital absence of the vas deferens. N. Engl. J. Med., 332, 1475–1480.
Dohle, G.R., Veeze, H.J., Overbeek, S.E. et al. (1999) The complex relationships between cystic fibrosis and congenital bilateral absence of the vas deferens: clinical, electrophysiological and genetic data. Hum. Reprod., 14, 371–374.
Dumur, V., Gervais, R., Rigot, J.M. et al. (1990) Abnormal distribution of CF DF508 allele in azoospermic men with congenital aplasia of epididymis and vas deferens. Lancet, 336, 512.[Web of Science][Medline]
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Submitted on March 22, 2001; accepted on June 22, 2001.
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