Multicolor PRINS and multicolor PNA

De novo cytogenetic alterations in spermatozoa of subfertile males might be due to genome instability associated with idiopathic male infertility: Experimental evidences and Review of the literature

Male infertility is caused by many factors including genetics. Although part of genetic damages are inherited and could be traced in blood leukocytes, but those de novo alterations induced in spermatogenesis are not part of diagnostic work up. De novo alterations might be the cause of many idiopathic conditions of male infertility. The aim of this study was to evaluate DNA damage, sex chromosomal aneuploidy and DAZ microdeletion in sperms of subfertile males in comparison with normal healthy individuals. Whole blood and semen samples were obtained from 75 subfertile and 45 normal men. Semen samples from karyotypically normal subfertile and normal individuals were used for DNA fragmentation, sex chromosome aneuploidy and DAZ microdeletion analysis. Sperm DNA damage was assessed by alkaline comet assay, chromosome aneuploidy and DAZ microdeletion was assessed using a combined primed in situ labeling and fluorescent in situ hybridization (PRINS-FISH) method. A significantly high percentage of DNA fragmentation was observed in subfertile patients compared to control. Similar observation was observed for sex chromosome aneuploidy and DAZ microdeletion (p < 0.01). A relatively small interindividual difference was seen in all three assays performed. However DAZ microdeletion was observed as mosaic form in Y bearing sperms. Results indicate that subfertile males experience higher genome instability in spermatogenesis expressed as DNA damage and consequently sperm chromosomal 220 AIMS Genetics Volume 3, Issue 4, 219-238. aneuploidy or microdeletions. Occurrence of de novo genetic alterations caused by environmental chemico-physical genotoxic agents during spermatogenesis might be one of the causes of idiopathic male infertility.

Efficient combined FISH and PRINS technique for detection of DAZ microdeletion in human sperm

Intracytoplasmic sperm injection (ICSI) now offers an effective therapeutic option for men with male infertility and is believed to allow transmission of genetically determined infertility to the male offspring. Transmission of DAZ (Deleted in Azoospermia) microdeletion is one of the major concerns for oligo and severe oligozoospermia patients. Screening of the Y chromosome microdeletion in the diagnostic work-up of infertile men is mainly done using polymerase chain reaction (PCR) on blood leukocytes. However, there are evidences showing that presence of DAZ in somatic cells might not be indicative of its presence in germ cell lineage. In this report we are going to describe a combined Primed in situ labeling (PRINS) and fluorescence in situ hybridization (FISH) technique to show the localization of DAZ gene as well as Y chromosome centromere on sperm nuclei. PRINS is a combination of FISH and in situ polymerization provides another approach for in situ chromosomal detection. In the present study the PRINS primers specific for DAZ genes and traditional direct labeled centromere FISH probes for Y and X chromosomes were used in order to simultaneously detect DAZ genes and sex chromosome aneuploidy in sperm samples.

[Cytogenetics of human spermatozoa: which interest?]

Incidence of aneuploidy in human spermatozoa could be detected by various methods for precise indications. Taking in consideration this aneuploidy rate could optimize the ICSI prognosis and genetic counselling.

Human interphase chromosomes: a review of available molecular cytogenetic technologies

Human karyotype is usually studied by classical cytogenetic (banding) techniques. To perform it, one has to obtain metaphase chromosomes of mitotic cells. This leads to the impossibility of analyzing all the cell types, to moderate cell scoring, and to the extrapolation of cytogenetic data retrieved from a couple of tens of mitotic cells to the whole organism, suggesting that all the remaining cells possess these genomes. However, this is far from being the case inasmuch as chromosome abnormalities can occur in any cell along ontogeny. Since somatic cells of eukaryotes are more likely to be in interphase, the solution of the problem concerning studying postmitotic cells and larger cell populations is interphase cytogenetics, which has become more or less applicable for specific biomedical tasks due to achievements in molecular cytogenetics (i.e. developments of fluorescence in situ hybridization -- FISH, and multicolor banding -- MCB). Numerous interphase molecular cytogenetic approaches are restricted to studying specific genomic loci (regions) being, however, useful for identification of chromosome abnormalities (aneuploidy, polyploidy, deletions, inversions, duplications, translocations). Moreover, these techniques are the unique possibility to establish biological role and patterns of nuclear genome organization at suprachromosomal level in a given cell. Here, it is to note that this issue is incompletely worked out due to technical limitations. Nonetheless, a number of state-of-the-art molecular cytogenetic techniques (i.e multicolor interphase FISH or interpahase chromosome-specific MCB) allow visualization of interphase chromosomes in their integrity at molecular resolutions. Thus, regardless numerous difficulties encountered during studying human interphase chromosomes, molecular cytogenetics does provide for high-resolution single-cell analysis of genome organization, structure and behavior at all stages of cell cycle.