Genetic screening in 2,710 infertile candidate couples for assisted reproductive techniques: results of application of Italian guidelines for the appropriate use of genetic tests

Detection of chromosome aberrations in 17 054 individuals with fertility problems and their subsequent assisted reproductive technology treatments in Central China

STUDY QUESTION

How do the types and frequency of chromosome aberrations in couples in central China affect fertility and ART treatment?

SUMMARY ANSWER

Men with chromosome aberrations or polymorphisms have an increased risk of semen quality impairment and infertility, and couples affected by reciprocal translocations had a lower pregnancy rate compared with other chromosome aberrations.

WHAT IS KNOWN ALREADY

Karyotyping is crucial for patients affected by infertility as chromosome aberrations play an important role in the etiology of male infertility. However, the influence of chromosome aberrations and polymorphisms on sperm motility and morphology remains controversial. Data on ART treatment outcomes in infertile couples affected by chromosome aberrations are insufficient.

STUDY DESIGN, SIZE, DURATION

We conducted a retrospective study involving 17 054 patients affected by infertility who underwent karyotyping in our center between January 2020 and May 2022.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Karyotyping was performed on 17 054 patients with reproductive failure. All patients were from the central regions of China. The following data were collected from a medical records system using patient identification numbers: couples' ages, history of pregnancy and childbirth, type of infertility, years of infertility, cause of infertility, chromosome karyotypes, semen analysis results, assisted reproductive techniques performed, and treatment outcomes of ART.

MAIN RESULTS AND THE ROLE OF CHANCE

The incidence of chromosome aberrations was 2.04%; 2.49% in men and 1.57% in women. By analyzing the relationships between chromosome aberrations/polymorphisms and abnormal semen parameters, we found that there were significantly higher rates of asthenozoospermia, oligospermia, and teratozoospermia among men with Robertsonian translocations and sex chromosomal structural aberrations compared with those with normal karyotypes. Higher rates of asthenozoospermia and teratozoospermia were also observed among men with autosomal reciprocal translocations. The incidence of chromosome aberrations in azoospermic men (13.75%), and in men with cryptozoospermia or severe oligospermia (6.97%) was significantly higher than that in men with mild oligospermia or normospermia (0.88-2.12%). In addition, we found that the progressive movement of sperm is impaired in men with Chromosome 21 polymorphisms compared with men with normal karyotypes (39.46% ± 20.51% vs 48.61% ± 18.76%, P = 0.026). The percentage of morphologically normal forms was lower in the chromosomal polymorphism group than in the normal karyotype group (5.01% ± 2.41% vs 5.59% ± 2.14%, P = 0.001), especially in men with polymorphisms on Chromosome 9 (enlarged Chromosome 9 heterochromatin [9qh+]: 4.48% ± 2.22% vs 5.59% ± 2.14%, P = 0.006; pericentric inversion of Chromosome 9 [inv(9)]: 5.09% ± 3.11% vs 5.59% ± 2.14%, P = 0.008). ART treatment was successful in 36.00% of couples affected by chromosome aberrations. However, couples affected by reciprocal translocations achieved a lower pregnancy rate (24.07%), which may be due to the lower euploidy rates (27.31%) when compared with that in other chromosome aberrations.

LIMITATIONS, REASONS FOR CAUTION

First, although the initial cohort was large, chromosome aberrations were identified in a small number of patients. Second, the observational nature of the study design is limiting. Third, the couples affected by infertility in this study were all outpatients that did not undergo identical comprehensive examinations except for karyotyping, leading to the incomplete collection of medical records. Also, the population included in this study mainly focused on couples affected by infertility, which may not be included in the European Association of Urology (EAU) recommendation on male infertility.

WIDER IMPLICATIONS OF THE FINDINGS

Men with chromosome aberrations or polymorphisms have an increased risk of semen quality impairment and infertility. Constitutional chromosome analysis is recommended for men affected by infertility and severe oligospermia or azoospermia to facilitate early and appropriate guidance for the most suitable treatment. Carriers of chromosome aberrations can achieve acceptable pregnancy outcomes through IVF. However, couples affected by reciprocal translocations have lower pregnancy rates, and more treatment cycles are needed before a successful pregnancy. A possible explanation may be the fewer euploid embryos obtained.

STUDY FUNDING/COMPETING INTEREST(S)

This work was supported by Grant 2021YFC2700603 from the National Key Research & Development Program of China. The authors declare no conflicts of interest.

TRIAL REGISTRATION NUMBER

N/A.

[Systematic karyotyping before ICSI: A necessary procedure? Analysis of case studies in the Nancy University Hospital Fertility Centre]

INTRODUCTION

A constitutional karyotype is often assayed for the couple before ICSI management. The objective of this study was to assess the prevalence of chromosomal abnormality in an infertile population, the impact on the care of couples and its cost.

METHODS

A single-center retrospective study was carried out at the Fertility Center of the University Hospital of Nancy, including all infertile couples who underwent a karyotype analysis from June 2009 to December 2016.

RESULTS

1252 couples were included. 7.9% had at least one abnormal karyotype. A change in care affected 22% of these couples, i.e. 1.7% of the total population. 9% of couples with karyotype abnormality underwent PGD. In the male population, the percentage of abnormal spermograms is significantly higher in the group with karyotype abnormality compared to the control group (85.7% vs. 46.5%, P<0.001).

DISCUSSION

The constitutional karyotype, due to its high economic and human cost, and limited interest, is a screening method for chromosomal abnormalities that has no place systematically before performing IVF. The future lies in the restriction of the indications for prescribing the karyotype as well as in the realization of PGS in targeted situations.

Criteria to evaluate patterns of segmental and complete aneuploidies in preimplantation genetic testing for aneuploidy results suggestive of an inherited balanced translocation or inversion

Objective

To define criteria for determining when preimplantation genetic testing for aneuploidy (PGT-A) results are suggestive of a potential balanced chromosomal rearrangement in the egg or sperm source and warrant karyotyping.

Design

Performance evaluation of criteria developed to assess PGT-A results for patterns of imbalances suggestive of a balanced chromosomal rearrangement in the egg or sperm source.

Setting

A single PGT-A laboratory and multiple in vitro fertilization centers.

Patients

Reproductive couples who underwent routine PGT-A testing.

Interventions

Karyotyping of reproductive couples for whom patterns of imbalances observed in PGT-A results suggested a balanced chromosomal rearrangement in the egg or sperm source.

Main Outcome Measures

Correct or incorrect flagging of predicted translocation in either the egg or sperm source based on chromosome analysis.

Results

Proposed criteria correctly predicted a balanced reciprocal translocation in 97% of cases (n = 33), a (13;14) Robertsonian translocation in all cases (n = 3), and an inversion in all cases (n = 2). Other criteria evaluated were determined to be ineffective because of relatively low occurrences that met the criteria and/or low predictive value.

Conclusions

Our results showed that the proposed criteria were effective for evaluating patterns of imbalances observed in PGT-A results suggestive of a potential chromosomal rearrangement in the egg or sperm source. Our proposed criteria can be employed by clinicians in the in vitro fertilization setting in combination with a patient's reproductive history to identify PGT-A patients who are likely carriers of balanced chromosomal rearrangements.

A systematic review and meta-analysis on the association between ICSI and chromosome abnormalities

BACKGROUND

In the decade following the introduction of ICSI, a higher prevalence of de novo chromosome abnormalities, in particular sex chromosome and autosomal structural abnormalities, as well as inherited abnormalities was described in children conceived by ICSI compared to both naturally conceived (NC) children and children conceived by standard IVF. The explanation for the observed increase in prevalence is not clear and has been suggested to reflect parental factors (e.g. age or sperm quality) or to be a result of the ICSI procedure itself. Over the years, the procedure, as well as the patient group, and indications for ICSI treatment have changed.

OBJECTIVE AND RATIONALE

The objective of this systematic review and meta-analysis was to assess the prevalence of chromosome abnormalities in ICSI pregnancies and children and to examine any potentially increased risk compared to standard IVF and NC.

SEARCH METHODS

Pubmed, Embase, Cochrane Libraries and Web of Science up to October 2020 were searched. Primary outcome measures were overall chromosome abnormalities and de novo abnormalities (including sex chromosome abnormalities and autosomal abnormalities). The secondary outcome was inherited abnormalities. We followed the PRISMA guidelines and relevant meta-analyses were performed.

OUTCOMES

The search included 4648 articles, out of which 27 met the inclusion criteria, and 19 were included in quantitative synthesis (meta-analyses). The prevalence of chromosome abnormalities varied considerably between studies, possibly explained by large differences in sample size and patient demographics. Only five studies were eligible for pooled analyses on adjusted data. All studies had a critical risk of bias. Results from pooled adjusted data showed no evidence of an increased risk of overall chromosome abnormalities when comparing ICSI to either standard IVF (aOR 0.75 (95% CI 0.41-1.38)) or NC (aOR 1.29 (95% CI 0.69-2.43)). In contrast, meta-analyses on unadjusted data showed an increased risk of overall chromosome abnormalities in ICSI compared to both standard IVF (OR 1.42 (95% CI 1.09-1.85)) and NC (OR 2.46 (95% CI 1.52-3.99)) and an increased risk of de novo abnormalities in ICSI compared to NC (OR 2.62 (95% CI 2.07-3.31)). Yet, based on a very low certainty of evidence, the conclusion remains, that no indication of an increased risk of chromosome abnormalities in ICSI offspring could be found. If an increased risk of chromosome abnormalities in selected ICSI offspring should exist, the absolute risk continues to be small.

WIDER IMPLICATIONS

This review provides an extensive overview of the existing evidence on the relationship between ICSI and chromosome abnormalities in the offspring. We highlight the need for well-designed large, prospective, controlled studies with systematic cytogenetic testing. Existing data are limited and, in many cases, marred by critical levels of bias.

Genetic counseling prior to assisted reproductive technology

BACKGROUND

Reproductive medicine deals with fertility and is closely related to heredity. In reproductive medicine, it is necessary to provide genetic information for the patients prior to assisted reproductive technology (ART). Japan Society for Reproductive Medicine (JSRM) requires doctors involved in reproductive medicine to have standard knowledge of reproductive genetics and knowledge of reproductive medicine, which is covered in their publication, "required knowledge of reproductive medicine."

METHODS

With the aim of providing straightforward explanations to patients in the clinical situation at pre-ART counseling, we provide the following five topics, such as (a) risk of birth defects in children born with ART, (b) chromosomal abnormalities, (c) Y chromosome microdeletions (YCMs), (d) possible chromosomal abnormal pregnancy in oligospermatozoa requiring ICSI (intracytoplasmic sperm injection), and (e) epigenetic alterations.

MAIN FINDINGS

The frequency of chromosome abnormalities in infertile patients is 0.595%-0.64%. YCMs are observed in 2%-10% of severe oligospermic men. High incidence of spermatozoa with chromosomal abnormalities has been reported in advanced oligospermia and asthenozoospermia that require ICSI. Some epigenetic alterations were reported in the children born with ART.

CONCLUSION

Certain genetic knowledge is important for professionals involved in reproductive medicine, even if they are not genetic experts.

Genetische Diagnostik vor assistierter Reproduktion – Empfehlungen der neuen S2k-Leitlinie 2019

Genetische Ursachen sind für etwa 10–20 % der männlichen und 5–10 % der weiblichen In- oder Subfertilität verantwortlich. Bei Männern ist die andrologische Untersuchung Voraussetzung dafür, genetische Ursachen von Spermatogenesestörungen einordnen zu können. Außer Störungen der Geschlechtschromosomen können auch balancierte Chromosomenumbauten zu einer Fertilitätsminderung führen. Eine Azoospermiefaktoranalyse in Bezug auf Y‑chromosomale Mikrodeletionen ist bei Männern mit Azoospermie indiziert, da sie über den Erfolg einer assistierten Reproduktion entscheiden kann. Bei Verdacht auf obstruktive Azoospermie soll eine Analyse des CFTR-Gens zur Diagnostik einer zystischen Fibrose erfolgen. Bei endokrinen Auffälligkeiten sind genetische Ursachen des häufigeren hypergonadotropen Hypogonadismus von denen eines seltenen kongenitalen hypogonadotropen Hypogonadismus zu unterscheiden. Algorithmen zur genetischen Diagnostik sind in der aktuellen Leitlinie im internationalen Vergleich ausgeführt.

Where are we going with gene screening for male infertility?

Male infertility is a heterogenous disease process requiring the proper functioning and interaction of thousands of genes. Given the number of genes involved, it is thought that genetic causes contribute to most cases of infertility. Identifying these causes, however, is challenging. Infertility is associated with negative health outcomes, such as cancer, highlighting the need to further understand the genetic underpinnings of this condition. This paper describes the genetic and genomic tests currently available to identify the etiology of male infertility and then will discuss emerging technologies that may facilitate diagnosis and treatment of in the future.

Somatic/gonadal mosaicism for structural autosomal rearrangements: female predominance among carriers of gonadal mosaicism for unbalanced rearrangements

Background

Mosaicism for chromosomal structural rearrangements (Rea) is rare and the timing and mechanisms of mosaic Rea formation, maintenance, and clinical manifestation are poorly understood. To date, there are no published data on the cytogenetic profile of mosaic Reas. The question as to whether the proportion of abnormal cells in the carrier’s cultured blood is clinically significant remains unanswered. A previous study showed a strong female preponderance among carriers of mosaicism for Rea with pericentromeric breaks, indicating female-specific instability in early embryos. However, there is no corresponding study on male to female sex ratio (SR) among carriers of somatic and/or gonadal mosaicism for non-centromeric Rea. Population rates of mosaic Rea carriers calculated from consecutive series of patients referred for various reasons and from prenatal samples have not been established. Therefore the objectives of the present study were several-fold: (1) a study on profiles of Rea involved, (2) comparative analysis of the proportion of cells with unbalanced Rea in blood cultures from asymptomatic and affected carriers, (3) comparative analysis of SR in carriers of mosaicism for balanced and unbalanced Rea, and (4) determination of the population frequency of mosaicism for autosomal Rea.

Results

One hundred and three cases of mosaicism for autosomal non-centromeric Rea (N/Rea; normal line/structural rearrangement) in which the sex of the carrier had been specified were identified in the literature. Among balanced Rea, there was a prevalence of reciprocal translocations (89 %) over inversions (11 %). Among unbalanced Rea, deletions were the most frequent (40 %), followed by duplications (25 %) and rings (16 %). Derivatives and other chromosome abnormalities were less frequent (9 and 10 %). Eight of eleven (73 %) affected carriers of unbalanced Rea displayed a high proportion (>50 %) of abnormal cells compared to 4/37 (11 %) in asymptomatic carriers, p < 0.0001. Among carriers of mosaicism for balanced Rea there was a slight male predominance, 24 M/22 F, unlike the strong female predominance among carriers of mosaicism for unbalanced Rea, 11 M/46 F, p < 0.0001. Among ten carriers of unbalanced Rea with reproductive failure, only one was a male with infertility, and one was a partner of a woman experiencing recurrent spontaneous abortion. Population rates of mosaics for reciprocal translocaton (N/rcp), inversion (N/inv), and unbalanced Rea (N/unbal Rea) calculated from published data on consecutive series of patients with reproductive failures were 0.02 ‰, 0.005 ‰, and 0.002 ‰, correspondingly. Among 30,376 infertile patients three carriers of mosaicism for balanced Rea were identified (two cases of N/rcp and one case of N/inv), whereas among 26,384 patients with habitual abortion seven carriers were detected (five N/rcp and two N/inv). Among all 56,760 tested patients with reproductive failures only one was found to be a carrier of mosaicism for an unbalanced Rea (N/del, mosaicism for deletion).

Conclusions

A high proportion of Rea cells (>50 %) detected in cultured T-lymphocytes is associated with clinical manifestation of chromosomal imbalance. A strong female prevalence among carriers of mosaicism for unbalanced Rea suggests male-specific selection against abnormal cells rather than impairment of male gametogenesis, as the latter suggests a better prognosis for male fetuses. These findings should be taken into consideration when genetic counseling of patients referred after a diagnosis of mosaicism for an unbalanced rearrangement in a fetus.

Alterations in the frequency of trinucleotide repeat dynamic mutations in offspring conceived through assisted reproductive technology

STUDY QUESTION

How does the frequency of trinucleotide repeat dynamic mutations in offspring conceived through assisted reproductive technology (ART) compare with the frequency of these mutations in control offspring conceived from spontaneous pregnancies?

SUMMARY ANSWER

There is a slight increase in dynamic mutation instability in offspring conceived through ART compared with the naturally conceived offspring.

WHAT IS KNOWN ALREADY

There is evidence to suggest that ART can increase the risk of birth defects and karyotypic abnormalities. However, the accumulating evidence of an association between ART and de novo genetic aberrations is controversial.

STUDY DESIGN, SIZE, DURATION

A prospective clinical observational study was performed on 246 families recruited from an in vitro fertilisation (IVF) centre at a tertiary-care, university-affiliated teaching hospital from 2008 to 2012. The study included 147 ART families [75 IVF and 72 intracytoplasmic sperm injection (ICSI)] in the study group and 99 natural-conception families in the control group.

PARTICIPANTS, SETTING, METHODS

Parental, umbilical cord and infant peripheral blood samples were collected, and the trinucleotide repeats of the ATN1, AR, ATXN1, ATXN3, Huntington, DMPK and FMR-1 genes were investigated between the generations; these genes were chosen due to their ability to undergo dynamic mutation. The frequencies and sizes of the mutational repeats, as well as the intergenerational instability, were measured.

MAIN RESULTS AND THE ROLE OF CHANCE

In 2466 transmissions identified in the ART offspring, 2.11% (n = 52/2466) of the alleles were unstable upon transmission, while in the control group offspring, the frequency of dynamic mutation was 0.77% (n = 10/1300); this difference was statistically significant (P < 0.01). The unstable transmission alleles were detected in 32 (2.48%) of the 1288 alleles from the IVF offspring and in 20 (1.70%) of the 1178 alleles from the ICSI offspring; both of these frequencies were significantly different from that of naturally conceived offspring (0.77%) (P < 0.01 and P < 0.05, respectively). However, there were no significant differences in the sizes of the mutational repeats or in the rates of expansion or contraction among the three groups (P > 0.05). The repeat copy numbers of the examined genes were found to be within the normal ranges in all parents and infants.

LIMITATIONS, REASONS FOR CAUTION

One strength of our study is the relatively large sample size; we were able to detect mutations in seven common dynamic genes, and this large sample size allowed us to detect unstable alleles. Although we observed a clear alteration in the frequency of dynamic mutation in the ART offspring compared with controls, further studies are urgently needed to confirm this observation and determine the cause of this phenomenon.

WIDER IMPLICATIONS OF THE FINDINGS

DNA microsatellite analysis provides an important tool to assess genomic instability. In this study, we report an association between ART and the frequency of dynamic mutation. The instability could be a reflection of the core infertility problem, the controlled ovarian hyperstimulation and/or the in vitro culture conditions.

Karyotype analysis in large-sample infertile couples living in Central China: a study of 14965 couples

OBJECTIVE

To explore that it is necessary to routinely detect chromosomes in fertile couples, we detected peripheral blood lymphocyte karyotype in 14965 infertile couples living in Central China and analyzed the incidence and type of chromosomal anomaly.

METHODS

G-banding karyotype analysis of peripheral blood lymphocytes was performed in 14965 couples who went to the outpatient department of our reproductive medical center for counseling on infertility between January 2004 and December 2011. Semen analysis was performed three times in all the men from the 14965 couples.

RESULTS

The rate of chromosomal anomaly in the 14965 infertile couples was 3.84 % (1150/29930). The rate of chromosomal anomaly in the men from 14965 couples was 6.84 % (1024/14965) and in the women 0.84 % (126/14965). The rates of chromosomal anomaly were 1.69 % in normal semen group, 11.82 % in light oligo-astheno-spermis group, 6.58 % in moderate to severe olig-astheno-spermia group and 17.26 % in azoospermia group.

CONCLUSION

Since the rates of chromosomal anomaly are 1.69 % and 11.82 % even in normal semen group and light oligo-astheno-spermia group, respectively, it is necessary to detect peripheral blood lymphocyte karyotype in all infertile couples.

Cytogenetic findings and reproductive outcome of infertile couples referred to an assisted reproduction program

It is still undefined whether all the couples entering an assisted reproduction program should undergo to karyotype analysis. The present study was conducted to determine the prevalence of chromosomal abnormalities in a non-selected sample of 1,146 couples referred to assisted reproduction technologies (ART), and to analyze the outcome of pregnancies from couples in whom cytogenetic anomalies were detected. Irrespective of the infertility factor, fertilization was achieved by intracytoplasmic sperm injection (ICSI). A total number of 35 karyotype anomalies were diagnosed, corresponding to an abnormality frequency of 1.52% (1.83% for men and 1.22% for women). As could be expected, the majority of men presenting karyotype anomalies had a low sperm count. Among women, the majority of cytogenetic anomalies were detected in individual not presenting risk factors for aberrant karyotype. Around 41% of pregnancies achieved in couples presenting chromosomal anomalies ended in spontaneous abortion. Information on fetal karyotype was limited. No major malformations were observed among newborns from parents with abnormal karyotype. In consideration of the elevated frequency of pregnancy loss, it seems advisable to recommend that chromosomal analysis be performed in all couples undergoing ART. This with the aim of identifying patients that would possibly benefit from pre-implantation genetic diagnosis.

CFTR mutation screening in an assisted reproductive clinic

INTRODUCTION

  Cystic fibrosis (CF) is the most common deleterious single-gene recessive disorder in non-Hispanic Caucasians. Mutations within the CF transmembrane receptor (CFTR) gene produce a variable phenotype, including pulmonary disease, pancreatic insufficiency, meconium ileus and infertility. Screening of antenatal/preconception patients to identify CFTR mutation carriers has been shown to reduce the incidence of CF-affected babies at birth. The application of preconception screening to assisted reproductive technology (ART) patients enables carrier couples a choice between prenatal screening and preimplantation genetic diagnosis (PGD).

AIM

  To screen patients entering an infertility clinic, for 30 common CFTR mutations, and to detect carrier patients prior to initiating assisted reproductive treatment.

METHOD

  DNA from 5600 infertility patients was screened using a PCR/OLA kit for 30 CFTR mutations. All identified carriers and carrier couples were offered genetic counselling. Prenatal testing and PGD for CFTR mutations were offered to carrier couples where appropriate.

RESULTS

  A total of 5600 patients were screened for 30 CFTR mutations with 261 carriers being identified and at a significantly increased carrier rate of one in 21.5 (4.66% ± 0.55%). R117H/c.350G>A was significantly increased in this infertile population and accounted for 13.8% of all mutations identified. Twelve carrier couples were identified, and nine carrier couples had at least one cycle of PGD for CFTR mutations.

CONCLUSION

  The carrier rate of CFTR mutations is elevated in patients presenting for infertility treatment, and preconception screening should be encouraged in all patients entering ART clinics.

Genetic screening in Italian infertile couples undergoing intrauterine insemination and in vitro fertilization techniques: a multicentric study

AIM OF THE STUDY

To report the frequency of aberrant karyotype and mutated cystic fibrosis transmembrane conductance regulator (CFTR) gene, according to a careful application of Italian guidelines for genetic screening in infertile couple candidates for intrauterine insemination (IUI) and in vitro fertilization/intracytoplasmic sperm injection (IVF/ICSI).

MATERIALS AND METHODS

Two thousand and sixteen consecutive infertile couple candidates for Assisted Reproduction Techniques (ART) were screened for karyotype and 616 couples for CFTR analysis.

RESULTS

Regarding karyotype analysis, 59 chromosomal abnormalities were diagnosed in candidates for IVF/ICSI: 27 mutations in women corresponding to a frequency equal to 1.53% (27/1762; 95% confidence interval [CI], 0.96-2.1%) and 32 mutations in men corresponding to a frequency equal to 1.82% (32/1762; 95% CI, 1.2-2.44%) for men. The frequency differs according to the sperm count. In couple candidates for IUI techniques, no genetic abnormalities were found in male patients and only one aberration in a female patient with a frequency of 0.41% (1/245 CI 0.01-0.81%). Regarding CFTR analysis, excluding the 5T variant, we obtained 20 mutations in couples undergoing IVF/ICSI and 8 mutations in IUI group.

CONCLUSION

Couples undergoing IVF/ICSI show a higher prevalence of aberrant karyotypes than general population, whereas the frequency of a mutation of the CFTR gene is similar. On the other hand, couples undergoing IUI do not differ from the general population either for karyotype or for CFTR mutations.

Enhanced frequency of CFTR gene variants in couples who are candidates for assisted reproductive technology treatment

BACKGROUND

An increased frequency of (cystic fibrosis transmembrane conductance regulator) CFTR mutations has been detected in some types of male infertility. The aim of this study was to shed light on the link between CFTR mutations and infertility.

METHODS

We sequenced the CFTR gene in 294 subjects (190 males) affected by infertility of different origin who underwent assisted reproductive technology (ART). As a control group, we studied 1000 (353 males) unrelated, unselected subjects from the general population of southern Italy.

RESULTS

The frequency of CFTR mutations, some of which are detected only by gene sequencing, and of the IVS8 poly(TG)12-poly(T)5-V470 haplotype was significantly higher in obstructive [congenital bilateral absence of vasa defer-entes (CBAVD, five cases)] and secretory (23 cases) azoospermic patients than in the general population. Some patients, primarily those with CBAVD, were compound heterozygous for two mutations. Interestingly, the frequency of the TG12-T5-V470 variant haplotype was significantly higher in severe oligospermic patients (88 cases) and in patients with tubal sterility (74 cases) compared with the general population. Finally, neither the frequency of CFTR mutations nor the frequency of the TG12-T5 variants differed between patients with mild oligospermia (74 cases) and patients with ovulatory sterility (30 cases) compared with the general population.

CONCLUSIONS

All subjects affected by obstructive or secretory azoospermia should undergo molecular analysis and counselling for CF using gene scanning which has a high detection rate and also reveals rare CFTR mutations. Molecular analysis seems to be less mandatory in other types of male/female infertility. Furthermore, we found that the CFTR TG12-T5-V470 variant haplotype was associated with both severe oligospermia and tubal infertility, thereby implicating the CFTR protein in both spermatogenesis and tubal functionality.