Supl. 1.

authors

Agnieszka Sobczyńska-Tomaszewska, Katarzyna Wertheim, Magdalena Nawara, Jan Karol Wolski1, Michał Radwan: Zakład Genetyki, Instytut Matki i Dziecka w Warszawie
Przychodnia Lekarska „Novum” w Warszawie
Centrum Leczenia Niepłodności „Gameta” w Łodzi

summary

Introduction.

Mutations in CFTR gene cause one of the commonest (1/2500 live births) autosomal recessive disorders: Cystic Fibrosis (CF). Mutations in the same gene are also identified in others diseases, i.e. male infertility due to CBAVD or obstructive azoospermia. Therefore CFTR mutations analysis is recommended in patients undergoing IVF. There are more than 1540 CFTR mutations known up-to-date. Depending on their effect on protein production – mutations can be divided into two distinct groups – severe and mild ones. Two severe mutations in trans lead to typical cystic fibrosis, whereas one severe mutation in trans with mild one alleviates the symptoms. Thus in

majority of patients with CBAVD or obstructive azoospermia two mutations are find (typically - one severe and the other mild, or, less often – both mild). In the case of azoospermia analysis of microdeletions of the Y chromosome should also be performed according to EAA/EMQN guidelines. This defect occurs in AZF region of Y chromosome, in which genes responsible for sperm production are located. There are three AZF regions- AZFa, AZFb, AZFc. AZFc microdeletions are the most common; AZFb, AZFbc, AZFa and AZFabc microdeletions are less frequent respectively. Deletions of AZFa and/or AZFb regions are in contradictory to TESE/ICSI procedure. Additionally patients with AZF deletions have increased potential risk of having offspring with 45, X0 Turner’s syndrome and other phenotypic anomalies associated with sex chromosome mosaicism.

Objectives.

We present the results of molecular analysis of 1169 azoospermic (obstructive and nonobstructive) men performed from 1997 to 2007 in Laboratory of Molecular Diagnostics of Infertility IMiD.

Materials and methods.

We have analyzed 1169 patients with azoospermia or CBAVD.

Standard molecular analysis covers 7 the most frequent mutations in CFTR gene in Polish population and/or AZFa (loci sY84 and 86), AZFb (loci sY127 and sY134), AZFc (loci sY254 and 255) microdeletions. CFTR mutation panel covered F508del, dele 2.3 (21 kb), R117H, G542X, G551D, R553X and the IVS8-5T variant. In several cases analysis was performed according to individual medical request.

Results. In 155 men (13.25%) we identified at least one mutation or IVS8-5T variant in CFTR gene. The most frequent defects were the IVS8-5T variant (93 alleles) and mutation F508del (27 alleles). In the group of patients with azoospermia, we fund 15 cases of microdeletions. The frequency of F508del carriers is slightly increased in our group of patients in comparison to expected values (1/43 vs1/45). Similarly, the frequency of IVS8-5T among these patients is just as was expected. In the group of CBAVD patients (46 men) eight F508del carriers were found. Thus, the frequency of F508del in his group was 8 times higher than expected (1/5, 75 vs. 1/45). Microdeletions in AZF region were not identified in CBAVD patients, what was in concordance with our expectations. Among AZF microdeletions identified in the remaining group of patients, the most frequent was microdeletion of AZFc, while microdeletions of AZFb and AZFbc were equally distributed.

Conclusions.

1. Obstructive azoospermia should then be recognized as indication for CFTR analysis, whereas nonobstructive azoospermia to AZF region test. 2. Due to the fact that testicular biopsy is often performed before ICSI procedure, and taking under consideration advantages of known CFTR/AZF status and relatively low costs of molecular tests, we would recommend performing both molecular analysis in obstructive and nonobstructive azoospermic men.