Male infertility is a multifactorial reproductive disorder. The effect of genetic factors on male infertility has been the focus of research. Although a variety of genetic techniques are applied to male infertility in clinical practice, karyotype analysis remains a powerful and inexpensive technology. Reciprocal chromosomal translocation (RCT) is closely related to male infertility, but the clinical phenotypes of RCT carriers are varied, and the underlying pathological mechanism is unclear. Some studies suggest that RCT breakpoints disrupt the structure and function of important genes responsible for spermatogenesis. Several breakpoints of chromosome 17 are related to important genes, which can lead to spermatogenic failure. This study aimed to identify the clinical features of 3 men with translocation karyotypes involving breakpoints on chromosome 17p13. Semen analysis and cytogenetic analysis were performed with informed consent. Gene ontology analysis was performed for 60 pathogenic genes on chromosome band 17p13. Cytogenetic analysis showed that the karyotypes were 46, XY, t(6;17) (p21;p13), 46,XY,t(10;17)(q11.2;p13), and 46, XY, t(17;20) (p13;q13), respectively. Relevant studies and genes on breakpoints on chromosome 17p13 were searched for using PubMed. Fourteen reported cases of the same karyotype were reviewed. The results suggest that although chromosome 17 is closely related to spermatogenic failure, the clinical phenotypes of RCT carriers with involvement of 17p13 breakpoints are varied. The important genes involved in the breakpoint were analyzed. The results of molecular functions suggested that these targets genes on chromosome band 17p13 were mostly involved in microfilament motor activity, ATPase activity. These results suggested that the translocation chromosome and breakpoint analysis should be considered in the clinical assessment of the patients. Physicians should be aware of these in genetic counseling. These breakpoints and the function of related genes require further study.

Aim Chromosome translocations are considered as one of the most severe forms of genome defects. Because of the clinical significance of chromosome translocations and scarce data on the incidence of sporadic translocations in population of Bosnia and Herzegovina, we aimed to report sporadic translocation frequencies in samples karyotyped in our laboratory. Methods The study group consisted of 108 samples. Whole blood was cultivated in complete medium for 72 hours with the thymidine application at 48th hour to synchronize the cell culture. Metaphases were arrested by colcemid 60 minutes before harvesting. Following hypotonic treatment, cells were fixed and cell suspension was dropped on coded slides. Dried slides were subjected to conventional GTG (G-banding with trypsin-Giemsa) banding and analyzed under 1000x magnification in the accordance with ISCN (International System for Human Cytogenetic Nomenclature) and E.C.A. Cytogenetic Guidelines and Quality Assurance. Results The incidence of all detected sporadic translocations was 27.81 x 10-4 per metaphase. The incidence of sporadic translocations involving chromosomes 7 and 14, being considered as the most frequent sporadic translocations of the human karyotype in phytohaemagglutinin (PHA) stimulated lymphocytes, was 15.89 x 10-4 per metaphase. The most frequent breakpoints were 7p21, 14q11 and 14q21. Other detected sporadic translocation breakpoints were: 1q25, 3p22, 7p13, 7q11.22, 7q33, 14q23 and 19q13.4. Conclusion Higher incidence of sporadic translocations compared to the similar studies was registered. Since potential explanations for this issue are smaller sample size and higher exposure of examined population to genotoxic agents, further monitoring of sporadic translocation incidences is recommended.

暂无摘要。

OBJECTIVE: To describe the chromosomal alterations in patients with mental retardation (MR) using G-banding karyotype analysis.
METHODS: A retrospective study of the results G-banding karyotype analysis of 369 patients investigated for MR was performed. Based on the structural rearrangements found, the authors searched all chromosomal regions related with breakpoints, and these were compared with the literature on MR and databases.
RESULTS: 338 (91.6%) normal cases, and 31 (8.4%) with some type of chromosomal abnormality were identified. Among the altered cases, 21 patients (67.8%) were identified with structural chromosomal alterations, nine (29%) with numerical alterations, and one (3.2%) with numerical and structural alterations.
CONCLUSIONS: Structural chromosomal abnormalities were observed more frequently in this study. G-banding karyotyping contributes to the investigation of the causes of MR, showing that this technique can be useful for initial screening of patients. However, higher resolution techniques such as array based comparative genomic hybridization (aCGH) and multiplex ligation-dependent probe amplification (MPLA) can detect submicroscopic alterations commonly associated with MR.

暂无摘要。

BACKGROUND: Osteoporosis is a systemic skeletal disease characterised by reduced bone mineral density and increased susceptibility to fracture; these traits are highly heritable. Both common and rare copy number variants (CNVs) potentially affect the function of genes and may influence disease risk.
OBJECTIVE: To identify CNVs associated with osteoporotic bone fracture risk.
METHODS: We performed a genome-wide CNV association study in 5178 individuals from a prospective cohort in the Netherlands, including 809 osteoporotic fracture cases, and performed in silico lookups and de novo genotyping to replicate in several independent studies.
RESULTS: A rare (population prevalence 0.14%, 95% CI 0.03% to 0.24%) 210 kb deletion located on chromosome 6p25.1 was associated with the risk of fracture (OR 32.58, 95% CI 3.95 to 1488.89; p = 8.69 × 10(-5)). We performed an in silico meta-analysis in four studies with CNV microarray data and the association with fracture risk was replicated (OR 3.11, 95% CI 1.01 to 8.22; p = 0.02). The prevalence of this deletion showed geographic diversity, being absent in additional samples from Australia, Canada, Poland, Iceland, Denmark, and Sweden, but present in the Netherlands (0.34%), Spain (0.33%), USA (0.23%), England (0.15%), Scotland (0.10%), and Ireland (0.06%), with insufficient evidence for association with fracture risk.
CONCLUSIONS: These results suggest that deletions in the 6p25.1 locus may predispose to higher risk of fracture in a subset of populations of European origin; larger and geographically restricted studies will be needed to confirm this regional association. This is a first step towards the evaluation of the role of rare CNVs in osteoporosis.

BACKGROUND: Recent advances in comparative genomics have considerably improved our knowledge of the evolution of mammalian karyotype architecture. One of the breakthroughs was the preferential localization of evolutionary breakpoints in regions enriched in repetitive sequences (segmental duplications, telomeres and centromeres). In this context, we investigated the contribution of ribosomal genes to genome reshuffling since they are generally located in pericentromeric or subtelomeric regions, and form repeat clusters on different chromosomes. The target model was the genus Mus which exhibits a high rate of karyotypic change, a large fraction of which involves centromeres.
RESULTS: The chromosomal distribution of rDNA clusters was determined by in situ hybridization of mouse probes in 19 species. Using a molecular-based reference tree, the phylogenetic distribution of clusters within the genus was reconstructed, and the temporal association between rDNA clusters, breakpoints and centromeres was tested by maximum likelihood analyses. Our results highlighted the following features of rDNA cluster dynamics in the genus Mus: i) rDNA clusters showed extensive diversity in number between species and an almost exclusive pericentromeric location, ii) a strong association between rDNA sites and centromeres was retrieved which may be related to their shared constraint of concerted evolution, iii) 24% of the observed breakpoints mapped near an rDNA cluster, and iv) a substantial rate of rDNA cluster change (insertion, deletion) also occurred in the absence of chromosomal rearrangements.
CONCLUSIONS: This study on the dynamics of rDNA clusters within the genus Mus has revealed a strong evolutionary relationship between rDNA clusters and centromeres. Both of these genomic structures coincide with breakpoints in the genus Mus, suggesting that the accumulation of a large number of repeats in the centromeric region may contribute to the high level of chromosome repatterning observed in this group. However, the elevated rate of rDNA change observed in the chromosomally invariant clade indicates that the presence of these sequences is insufficient to lead to genome instability. In agreement with recent studies, these results suggest that additional factors such as modifications of the epigenetic state of DNA may be required to trigger evolutionary plasticity.

PAX5 is the main target of somatic mutations in acute B lymphoblastic leukemia (B-ALL). We analyzed 153 adult and child B-ALL harboring karyotypic abnormalities at chromosome 9p, to determine the frequency and the nature of PAX5 alterations. We found PAX5 internal rearrangements in 21% of the cases. To isolate fusion partners, we used classic and innovative techniques (rolling circle amplification-rapid amplification of cDNA ends) and single nucleotide polymorphism-comparative genomic hybridization arrays. Recurrent and novel fusion partners were identified, including NCoR1, DACH2, GOLGA6, and TAOK1 genes showing the high variability of the partners. We noted that half the fusion genes can give rise to truncated PAX5 proteins. Furthermore, malignant cells carrying PAX5 fusion genes displayed a simple karyotype. These data strongly suggest that PAX5 fusion genes are early players in leukemogenesis. In addition, PAX5 deletion was observed in 60% of B-ALL with 9p alterations. Contrary to cases with PAX5 fusions, deletions were associated with complex karyotypes and common recurrent translocations. This supports the hypothesis of the secondary nature of the deletion. Our data shed more light on the high variability of PAX5 alterations in B-ALL. Therefore, it is probable that gene fusions occur early, whereas deletions should be regarded as a late/secondary event.