A large proportion of patients with oligoasthenoteratozoospermia (OAT) have an abnormal karyotype and hence they produce aneuploid gametes. However, a normal karyotype does not exclude the chance of having germ cell aneuploidy, since an altered intra-testicular environment not only damages spermatogenesis, but may also disrupt the mechanisms controlling chromosomal segregation during meiosis. Therefore, this study was undertaken to evaluate the rate of aneuploidy in the spermatozoa of selected patients with abnormal sperm parameters. For this purpose, sperm aneuploidy rate for chromosomes 8, 12, 18, X and Y was evaluated by multicolour fluorescence in-situ hybridization (FISH) in nine patients with teratozoospermia alone and 19 OAT patients of presumably testicular origin. Thirteen normozoospermic healthy men served as controls. Patients with teratozoospermia or OAT had significantly greater disomy and diploidy rates compared with controls, whereas the rate of nullisomy was similar. XY disomy was very low in all groups, suggesting that chromosomal non-disjunction occurs mainly during the second meiotic division. Autosome 12 disomy rate was low in both patients and controls. There was a marked variability of total sperm aneuploidy rate in both groups of patients. Sperm aneuploidy rate was negatively correlated with sperm concentration and particularly with the percentage of normal forms. In conclusion, patients with teratozoospermia or OAT have an increased rate of sperm aneuploidy. This increase is similar in both groups, suggesting that teratozoospermia may be the critical sperm parameter associated with aneuploidy.
Infertile patients with abnormal sperm parameters have an increased sperm aneuploidy rate, despite a normal blood karyotype. The evaluation of sperm chromosome aberrations in patients with teratozoospermia only has shown a rate similar to that found in patients exhibiting oligo-astheno-teratozoospermia, which suggests that teratozoospermia is the critical parameter associated with aneuploidy. However, it is not known which alteration of the sperm morphology is associated with chromosome aberrations. The few cases reported so far have shown an association with the presence of abnormal head morphology and particularly with enlarged heads. We report the sperm aneuploidy rate of 3 patients with oligo-asthenozoospermia who have absolute teratozoospermia (100% abnormal forms) and a different percentage of sperm head abnormalities. Fourteen healthy men with normozoospermia served as control subjects. Sperm aneuploidy and diploidy rates were calculated by using triple-color fluorescence in situ hybridization (FISH) for chromosomes 12, X, and Y, and double-color FISH was used for chromosomes 8 and 18. Patient K53, who had the highest number of spermatozoa with enlarged heads (54.3%), also had the highest aneuploidy and diploidy rates. The other 2 patients, K56 and K61, had sperm aneuploidy and diploidy rates lower than those of patient K53 but still well above the range found in normal men. Sperm chromosome abnormalities were intermediate in patient K61 and lower in patient K56, who had the lowest rate of spermatozoa with enlarged heads (18.9%). These data add further evidence that patients with teratozoospermia have an increased sperm aneuploidy rate and that this is particularly high in presence of an elevated percentage of spermatozoa with enlarged heads. For this reason, germ cells exhibiting this abnormality should not be used in in vitro fertilization programs.
Azoospermic patients can now father children once spermatozoa have been retrieved from the epididymis or the testis. However, there are concerns about the risk of chromosomal abnormalities since an increase in sperm aneuploidy rate has been reported in samples from patients with abnormal sperm parameters. The purpose of this study was therefore to evaluate the sperm aneuploidy and diploidy rates for chromosomes 8, 12, 18, X and Y in spermatozoa extracted from the epididymes (n=10) or the testes (n=6) of patients with azoospermia. Ejaculated spermatozoa of healthy men (n=14) served as control. Epididymal and testicular spermatozoa had an aneuploidy rate significantly higher than that found in ejaculated spermatozoa. The aneuploidy and diploidy rates of testicular spermatozoa were higher, but not significantly different, than those found in epididymal spermatozoa. This study has shown that azoospermic patients have an increased sperm aneuploidy rate. They should therefore be given appropriate genetic counselling before entering in-vitro fertilisation programs.
The possibility of retrieving spermatozoa from the epididymis allows patients with congenital bilateral absence of the vas deferens (CBAVD) to father a child by means of assisted reproduction techniques. This has, however, increased the chance of transmitting a mutated allele of the cystic fibrosis transmembrane conductance regulator (CFTR) gene which increases the risk of generating offspring with cystic fibrosis (CF). Because of the increased heterogeneity of the CFTR locus, the study of a discrete number of mutations, as usually carried out in a diagnostic work-up, is unable to ascertain the presence of a mutation in a relatively high proportion of the patients screened. In an attempt to increase the chance of detecting the presence of CFTR gene abnormalities, 37 patients with CBAVD and one patient with congenital unilateral agenesis of the vas deferens (CUAVD) underwent an enlarged diagnostic protocol, which included screening for the most expected mutations of the CFTR gene in our population, evaluation of the five thymidine (5T) allelic variant, sweat test, respiratory function tests, evaluation of steatocrit, and an accurate evaluation of the history of the patient to search for symptoms commonly found in patients with CF. A single CFTR gene mutation was found in 18 patients (48.6%) with CBAVD and in the patient with CUAVD. The most frequent mutation observed was the Delta F508. Eleven patients (45.8%) had the 5T variant and in five of them it was not associated with any detectable mutation of the CFTR gene. Two female partners were found to be carriers of a mutation, whereas 5 (18.5%) had the 5T variant. As many as 71% of CBVAD patients had the simultaneous presence of at least two signs and/or symptoms suggestive of CF, albeit they were of mild intensity and the patients felt fit and healthy. In conclusion, these results suggested that some patients with CBAVD without CFTR gene mutation or 5T variant, even when their sweat test is negative, may show clinical suspicion of carrying a CFTR gene mutation and therefore are at risk of generating children affected by CF if the partner carries a mutation as well. The screening for mutations and a careful clinical examination may contribute to better identification of patients with CFTR-related CBAVD.
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