(1/870) Chromosome abnormalities in sperm from infertile men with asthenoteratozoospermia.
Research over the past few years has clearly demonstrated that infertile men have an increased frequency of chromosome abnormalities in their sperm. These studies have been further corroborated by an increased frequency of chromosome abnormalities in newborns and fetuses from pregnancies established by intracytoplasmic sperm injection. Most studies have considered men with any type of infertility. However, it is possible that some types of infertility have an increased risk of sperm chromosome abnormalities, whereas others do not. We studied 10 men with a specific type of infertility, asthenozoospermia (poor motility), by multicolor fluorescence in situ hybridization analysis to determine whether they had an increased frequency of disomy for chromosomes 13, 21, XX, YY, and XY, as well as diploidy. The patients ranged in age from 28 to 42 yr (mean 34.1 yr); they were compared with 18 normal control donors whose ages ranged from 23 to 58 yr (mean 35.6 yr). A total of 201 416 sperm were analyzed in the men with asthenozoospermia, with a minimum of 10 000 sperm analyzed per chromosome probe per donor. There was a significant increase in the frequency of disomy in men with asthenozoospermia compared with controls for chromosomes 13 and XX. Thus, this study indicates that infertile men with poorly motile sperm but normal concentration have a significantly increased frequency of sperm chromosome abnormalities. (+info)
(2/870) Alpha-satellite DNA and vector composition influence rates of human artificial chromosome formation.
Human artificial chromosomes (HACs) have been proposed as a new class of potential gene transfer and gene therapy vector. HACs can be formed when bacterial cloning vectors containing alpha-satellite DNA are transfected into cultured human cells. We have compared the HAC-forming potential of different sequences to identify features critical to the efficiency of the process. Chromosome 17 or 21 alpha-satellite arrays are highly competent HAC-forming substrates in this assay. In contrast, a Y-chromosome-derived alpha-satellite sequence is inefficient, suggesting that centromere specification is at least partly dependent on DNA sequence. The length of the input array is also an important determinant, as reduction of the chromosome-17-based array from 80 kb to 35 kb reduced the frequency of HAC formation. In addition to the alpha-satellite component, vector composition also influenced HAC formation rates, size, and copy number. The data presented here have a significant impact on the design of future HAC vectors that have potential to be developed for therapeutic applications and as tools for investigating human chromosome structure and function. (+info)
(3/870) Genetic follow-up of male offspring born by ICSI, using a multiplex fluorescent PCR-based test for Yq deletions.
De-novo deletions involving AZFa, b, c and d are one of the most common chromosomal aberrations in man resulting in defective spermatogenesis and male infertility. Currently, Yq deletion screening involves either single or multiplex PCR using Y-specific sequence tagged site markers and the subsequent analysis of the amplification products on ethidium bromide-stained agarose gels. To improve the practicality of routine and high throughput Yq testing, we have developed a more sensitive multiplex fluorescent (FL)-PCR screening system using genomic DNA extracted from cheek buccal cells as a readily available PCR template. For genetic follow-up studies of ICSI-conceived children, we also developed a DNA fingerprinting system based on the co-amplification of four highly polymorphic markers to validate family samples and detect any potential extraneous DNA contamination that could cause a misdiagnosis. Multiplex FL-PCR analysis of buccal cell DNA from two infertile men who conceived three sons by ICSI demonstrated that their Yq deletions were vertically transmitted. Fine mapping with additional Yq markers revealed identical deletion endpoints involving the loss of AZFdc sequences. This firstly indicates that the extent of the Yq deletion was unchanged on ICSI transmission and secondly supports the view that AZFdc deletions may arise by a common de-novo event. Analysis of paternal, maternal and sibling DNA fingerprints showed the co-inheritance of parental alleles by each male child and confirmed the expected relationship between each family member. The application of these new FL-PCR based screening tests in genetic follow-up studies will assist in confirming transmission of specific genetic defects to male offspring conceived by ICSI and provide a basis for genetic counselling and potential treatment options as these boys approach sexual maturity. (+info)
(4/870) Transmission of male infertility to future generations: lessons from the Y chromosome.
The introduction of ICSI and testicular sperm extraction (TESE) has allowed many infertile men to father children. The biggest concern about the wide use of these techniques is the health of the resulting offspring, in particular their fertility status. If the spermatogenic defect is genetic in origin, there is potential risk of transmitting this defect to future offspring. The most frequently documented genetic cause of male infertility is a Y chromosome deletion. The Y chromosome has acquired a large number of testis-specific genes during recent evolution, and deletions causing infertility take out a number of these genes. These deletions have been shown to be transmitted to 100% of male offspring. Also, absence of an aberration on the Y chromosome does not rule out a genetic cause of the infertility phenotype, as there are many other genes involved in spermatogenesis elsewhere in the genome, and current mapping techniques--especially on the Y chromosome--can miss many aberrations. More detailed studies of these spermatogenesis genes, which are now possible because of more precise sequence-based mapping, will lead to improved understanding of the genetic basis of male infertility and enable proper counselling of patients undergoing ICSI in the future. (+info)
(5/870) Microdeletions in the Y chromosome of patients with idiopathic azoospermia.
AIM: To evaluate the occurrence and prevalence of microdeletions in the gamma chromosome of patients with azoospermia. METHODS: DNA from 29 men with idiopathic azoospermia was screened by polymerase chain reaction (PCR) analysis with a set of gamma chromosome specific sequence-tagged sites (STSs) to determine microdeletions in the gamma chromosome. RESULTS: Deletions in the DAZ (deleted in azoospermia) loci sgamma254 and sgamma255 were found in three patients with idiopathic azoospermia, resulting in an estimated frequency of deletions of 10.7% in idiopathic azoospermia men. CONCLUSION: We conclude that PCR analysis is useful for the diagnosis of microdeletions in the Y chromosome, which is important when deciding the suitability of a patient for assisted reproductive technology such as testicular sperm extracion-intracytoplasmic sperm injection (TESE-ICSI). (+info)
(6/870) Sperm aneuploidy rates in younger and older men.
BACKGROUND: In order to assess the possible risk of chromosomal abnormalities in offspring from older fathers, we investigated the effects of age on the frequency of chromosomal aneuploidy rates of human sperm. METHODS AND RESULTS: Semen samples were collected from 15 men aged <30 years (24.8 +/- 2.4 years) and from eight men aged >60 years (65.3 +/- 3.9 years) from the general population. No significant differences in ejaculate volume, sperm concentration and sperm morphology were found, whereas sperm motility was significantly lower in older men (P = 0.002). For the hormone values, only FSH was significantly elevated in the older men (P = 0.004). Multicolour fluorescence in-situ hybridization was used to determine the aneuploidy frequencies of two autosomes (9 and 18); and of both sex chromosomes using directly labelled satellite DNA probes on decondensed sperm nuclei. A minimum of 8000 sperm per donor and >330 000 sperm in total were evaluated. The disomy rates per analysed chromosomes were 0.1-2.3% in younger men and 0.1-1.8% in older men. The aneuploidy rate determined for both sex chromosomes and for the autosomes 9 and 18 were not significantly different between the age groups. CONCLUSIONS: The results suggest that men of advanced age still wanting to become fathers do not have a significantly higher risk of procreating offspring with chromosomal abnormalities compared with younger men. (+info)
(7/870) Achievement of pregnancy in globozoospermia with Y chromosome microdeletion after ICSI.
Pregnancy achieved with sperm from a patient with globozoospermia is rare, even after ICSI, since the activation of the oocyte may not occur in this disorder. Therefore, activation of the oocytes by piezoelectricity or calcium ionophores has been suggested, although spontaneous activation of the oocyte after ICSI has been reported in some cases. We report a successful pregnancy in a couple in which the male partner had globozoospermia with microdeletions in the Y chromosome with no further assisted activation after ICSI. During the diagnostic study of the husband, increased numerical chromosome abnormalities after fluorescent in-situ hybridization (FISH) and microdeletions in AZFa; sY86 and AZFb; sY 131 were detected. Out of the 13 oocytes injected, four fertilized and a twin pregnancy was obtained after replacement of four embryos. Healthy twin girls were delivered after a term pregnancy. Some patients with globozoospermia may also have Y chromosome microdeletions, which subsequently may be inherited by the male offspring in cases of achievement of pregnancy. (+info)
(8/870) Y-chromosome microdeletions and cytogenetic findings in unselected ICSI candidates at a Danish fertility clinic.
PURPOSE: To determine the frequency and type of microdeletions on the Y chromosome, and to evaluate cytogenetic findings in unselected ICSI candidates at a Danish Fertility Clinic. METHODS: Genomic DNA was extracted from blood samples, which were collected prospectively from 400 ICSI candidates attending the Fertility Clinic at Aarhus University Hospital, Denmark. Twenty-five sequence tagged sites (STSs) spanning the azoospermia factor (AZF) regions of the Y chromosome were amplified in 5 multiplex sets to investigate Y microdeletions. Semen analysis, karyotype analysis, and histological evaluation of testicular biopsies were also performed. RESULTS: Y microdeletions were detected in 3 (0.75%) of 400 unselected ICSI candidates. The frequency of Y microdeletions was found higher in azoospermic men (2%) than in oligozoospermic men (0.6%). Two patients having oligozoospermia had Y microdeletions in the AZFc region only, whereas the patient having azoospermia had Y microdeletions spanning the AZFb and AZFc regions. No microdeletion was detected in the AZFa region. Chromosomal anomalies were found in 6.1% of azoospermic men and in 2.7% of oligozoospermic men. A high frequency of cytogenetic abnormalities was found in normozoospermic men with fertilization failure (7.4%). CONCLUSIONS: The frequency of Y microdeletions both in the unselected ICSI candidates and subgroups classified as azoospermic and oligozoospermic seems rather low compared to results of previous studies, which have been quite varying. It is possible that in addition to patient selection criteria, ethnical and geographical differences may contribute to these variations. Cytogenetic evaluation of normozoospermic men with fertilization failure seems indicated because of a high frequency of cytogenetic abnormalities. (+info)