Reciprocal translocation and Robertsonian translocation in relation to semen parameters: A retrospective study and systematic review

Swimming trapper decreases the proportion of chromosomally unbalanced spermatozoa in human Robertsonian translocation carriers

BACKGROUND

Carriers of reciprocal translocations often have more unbalanced spermatozoa and higher DNA fragmentation rates, elevating reproductive risk. The simple swim-up method (SSUM) can decrease the amount of spermatozoa with abnormal chromatin structure and fragmented DNA, however, it has limited efficacy in eliminating chromosomally unbalanced sperm.

METHODS

The spermatozoa of eight Robertsonian translocation (Rob) carriers were split into three groups: original raw semen group (control group); SSUM and swimming trapper method group (STM) processed semen samples. After different semen preparation procedures, semen qualities, sperm chromosomal aneuploidy, and sperm fragmented DNA were evaluated.

RESULTS

Although spermatozoa with higher motility was obtained by both SSUM and STM, the population of faster forward moving sperm was greater with STM as compared to SSUM. While the rates of DNA fragmentation were statistically much lower in both groups than ejaculated semen sample, our data showed better effect on the decrease of DNA fragmentation index (DFI) after selection by STM for patients who have high DFI (>20%) in neat semen. For all patients, significant decrease in the frequency of chromosomally unbalanced spermatozoa was observed after selection using STM. Although similar trends can be seen in the SSUM group, a significant difference was identified in one patient only.

CONCLUSIONS

Use of swimming trapper (STM) is superior for enriching high-motile and genetically competent sperm in comparison with SSUM.

Analysis of 2 men with t(8;22)(q13;q13) and t(8;14)(q13;q22) chromosomal translocation karyotypes

Male infertility is a multifactorial condition that is closely associated with chromosomal abnormalities. Reciprocal chromosomal translocation (RCT) is a significant structural genetic abnormality. The specific mechanisms of forms of RCT affecting male infertility include the product of chromosomally unbalanced gametes, thereby disrupting the structure and function of important genes responsible for spermatogenesis. RCT breakpoints have been found to disrupt gene structure and function in many medical fields However, the relationship between RCT breakpoints and male infertility remains to be determined. The purpose of this study is to describe 2 male carriers of RCTs 46,XY,t(8;22)(q13;q13) and 46,XY,t(8;14)(q13;q22). Both patients were collected from the second hospital of Jilin University. Semen parameters were detected using the computer-aided semen analysis system. Cytogenetic analysis was performed using standard operating procedure. Related genes on chromosomal breakpoints were searched using Online Mendelian Inheritance in Man. One man had semen parameters within the normal range, but the couple was infertile after 5 years of marriage. The other man showed normal semen parameters, and his wife had experienced 2 spontaneous miscarriages. Using a literature search, the association between chromosome 22q13 breakpoint and fertility were investigated. The results suggest that physicians should focus on the clinical phenotype of the patients and the breakpoints of RCT in genetic counseling. An important gene related to human male infertility is clearly located in chromosome region 22q13, and its function is worthy of further study.

Association between chromosome 22q11.2 translocation and male oligozoospermia

Chromosomal aberrations in peripheral blood are a major cause of reproductive disorders for the infertile couples. Reciprocal translocation is closely related to male infertility. The breakpoint of translocation may disrupt or dysregulate important genes related to spermatogenesis. The relationship between some breakpoints of chromosome and male infertility has been paid attention. Chromosome 22q11.2 translocation has not been reported with male infertility. The purpose of this study is to evaluate the relationship between chromosome 22q11.2 translocation and male infertility. All patients were collected from the second hospital of Jilin University. Semen parameters were detected using the computer-aided semen analysis system. Cytogenetic analysis was performed using standard operating procedure. Related genes on chromosomal breakpoints were searched using online mendelian inheritance in man (OMIM). The association between this breakpoint and spermatogenesis is also discussed. We report 6 cases of translocation in chromosome 22. Of 7 breakpoints involved in these translocations, the common feature is that they all included chromosome 22q11.2 translocation and presented with oligozoospermia. The analysis of breakpoint related genes showed testis-specific serine/threonine kinase 2 (TSSK2) gene is associated with human spermatogenesis impairment. Overall, these results suggest that the breakpoint involved in translocation deserves attention from physicians in genetic counseling. The breakpoint rearrangement has the possibility of disrupting spermatogenesis. The relationship between 22q11.2 breakpoint and male infertility deserves further study.

The relevance of sperm morphology in male infertility

This brief report concerns the role of human sperm morphology assessment in different fields of male infertility: basic research, genetics, assisted reproduction technologies, oxidative stress. One of the best methods in studying sperm morphology is transmission electron microscopy (TEM) that enables defining the concept of sperm pathology and classifying alterations in non-systematic and systematic. Non-systematic sperm defects affect head and tail in variable ratio, whereas the rare systematic defects are characterized by a particular anomaly that marks most sperm of an ejaculate. TEM analysis and fluorescence in situ hybridization represent outstanding methods in the study of sperm morphology and cytogenetic in patients with altered karyotype characterizing their semen quality before intracytoplasmic sperm injection. In recent years, the genetic investigations on systematic sperm defects, made extraordinary progress identifying candidate genes whose mutations induce morphological sperm anomalies. The question if sperm morphology has an impact on assisted fertilization outcome is debated. Nowadays, oxidative stress represents one of the most important causes of altered sperm morphology and function and can be analyzed from two points of view: 1) spermatozoa with cytoplasmic residue produce reactive oxygen species, 2) the pathologies with inflammatory/oxidative stress background cause morphological alterations. Finally, sperm morphology is also considered an important endpoint in in vitro experiments where toxic substances, drugs, antioxidants are tested. We think that the field of sperm morphology is far from being exhausted and needs other research. This parameter can be still considered a valuable indicator of sperm dysfunction both in basic and clinical research.