This work focuses on the distribution of LINE-1 (a Long Interspersed Nuclear Element) in primates and its role during evolution and as a constituent of the architecture of primate genomes. To pinpoint the LINE-1 repeat distribution and its role among primates, LINE-1 probes were mapped onto chromosomes of Homo sapiens (Hominidae, Catarrhini), Sapajus apella, and Cebus capucinus (Cebidae, Platyrrhini) using fluorescence in situ hybridisation (FISH). The choice of platyrrhine species are due to the fact they are taxa characterised by a high level of rearrangements; for this reason, they could be a useful model for the study of LINE-1 and chromosome evolution. LINE-1 accumulation was found in the two Cebidae at the centromere of almost all acrocentric chromosomes 16-22 and on some bi-armed chromosomes. LINE-1 pattern was similar in the two species but only for chromosomes 6, 8, 10, and 18, due to intrachromosomal rearrangements in agreement with what was previously hypothesised as through g banding. LINE-1 interstitial accumulation was found in humans on the 1, 8, 9, 13-15, and X chromosomes; on chromosomes 8, 9, and 13-15, the signal was also at the centromeric position. This is in agreement with recent and complete molecular sequence analysis of human chromosomes 8 and some acrocentric ones. Thus, the hypothesis regarding a link between LINE-1 and centromeres as well as a link with rearrangements are discussed. Indeed, data analysis leads us to support a link between LINE-1 and inter- and intrachromosomal rearrangements, as well as a link between LINE-1 and structural functions at centromeres in primates.

Chronic myeloid leukemia (CML) is characterized by the reciprocal translocation between chromosomes 9 and 22: t(9;22)(q34;q11). However, 5-10% of patients with CML have complex variant translocations involving at least a third chromosome; only a few cases affect the X chromosome. Therefore, the data available regarding their features and the response to treatment is limited. In the present report, a case of a variant Philadelphia translocation t(X;9;22)(q22?;q34;q11.2) identified in a 51-year-old female with a newly diagnosed CML is described. The patient was treated with nilotinib. A major molecular response was observed after 12 months of starting treatment. Deep molecular response was obtained 20 months later and maintained after the 110-month follow-up. Additionally, a literature review was performed, with the aim of comprehending the complex clinical and biological characteristics of CML cytogenetic variants involving the X chromosome.

BACKGROUND: Xp11.2 translocation renal cell carcinoma (tRCC) is recently recognized. As Xp11.2 tRCC involved gene translocation and fusion in X chromosome and the number of X chromosomes in female is twice of male, we wondered whether the gender difference of attack rate is consistent with the proportion of the X chromosome.
METHODS: In the present paper, meta-analysis was performed to find out the difference of morbidity between male and female.
RESULTS: Nine studies with 209 cases calculated. Odds ratios (ORs) and ORs with 95% confidence intervals (CIs) were calculated for attack rate of Xp11.2 RCC with different gender. The result showed that the attack rate of female was higher than that of male with pooled OR of 2.84 (95% CI = 1.48-5.45), while the rate rises even further in adult (OR = 3.37, 95% CI =2.19-5.18). In other types of common kidney cancer, the OR value is less than 1, which means that the incidence of female is lower than that of male.
CONCLUSIONS: The result showed that the incidence rate of female patients is much higher than that of male patients with Xp11.2 tRCC, it was reasonable to indicate that this particular incidence rate is related to the X chromosome.

Successful fertilization in mammals requires spermatozoa to efficiently traverse the female reproductive tract to meet the egg. This process naturally selects high quality sperm cells for fertilization, but when artificial reproductive technologies are used such as in vitro fertilization, intracytoplasmic sperm injection, or intrauterine insemination, other methods of sperm selection are required. Currently, technology enables sperm sorting based on motility, maturity as defined by zeta potential or hyaluronic acid binding site expression, absence of apoptotic factors, appropriate morphology, and even sex. This review summarizes current knowledge on all known methods of sperm cell sorting, compares their efficiency, and discusses the advantages and limitations of each technique. Scope for further refinement and improvement of current methods are discussed as is the potential to utilize a variety of materials to innovate new methods of sperm separation.

Fragile X syndrome (FXS) is a genetic condition known to increase the risk of cognitive impairment and socio-emotional challenges in affected males and females. To date, the vast majority of research on FXS has predominantly targeted males, who usually exhibit greater cognitive impairment compared to females. Due to their typically milder phenotype, females may have more potential to attain a higher level of independence and quality of life than their male counterparts. However, the constellation of cognitive, behavioral, and, particularly, socio-emotional challenges present in many females with FXS often preclude them from achieving their full potential. It is, therefore, critical that more research specifically focuses on females with FXS to elucidate the role of genetic, environmental, and socio-emotional factors on outcome in this often-overlooked population.

The \"X chromosome-nucleolus nexus\" hypothesis provides a comprehensive explanation of how autoantibodies can develop following cellular stress. The hypothesis connects autoimmune diseases with the impact of environmental factors, such as viruses, through epigenetic disruption. The inactive X chromosome, a major epigenetic structure in the female cell\'s nucleus, is a key component of the hypothesis. The inactive X is vulnerable to disruption due to the following: (1) its heavy requirements for methylation to suppress gene expression, (2) its peripheral location at the nuclear envelope, (3) its late replication timing, and (4) its frequently observed close association with the nucleolus. The dynamic nucleolus can expand dramatically in response to cellular stress and this could disrupt the neighboring inactive X, particularly during replication, leading to expression from previously suppressed chromatin. Especially vulnerable at the surface of the inactive X chromosome would be genes and elements from Xp22 to the terminus of the short arm of the X. Expression of these genes and elements could interfere with nucleolar integrity, nucleolar efficiency, and future nucleolar stress response, and even lead to fragmentation of the nucleolus. Ribonucleoprotein complexes assembled in the nucleolus could be left in incomplete states and inappropriate conformations, and/or contain viral components when the nucleolus is disrupted and these abnormal complexes could initiate an autoimmune response when exposed to the immune system. Epitope spreading could then lead to an autoimmune reaction to the more abundant normal complexes. Many autoantigens reported in lupus and other autoimmune diseases are, at least transiently, nucleolar components.

The X chromosome has long been an intriguing site for harboring genes that have importance in brain development and function. It has received the most attention for having specific genes underlying the X-linked inherited intellectual disabilities, but has also been associated with schizophrenia in a number of early studies. An X chromosome hypothesis for a genetic predisposition for schizophrenia initially came from the X chromosome anomaly population data showing an excess of schizophrenia in Klinefelter\'s (XXY) males and triple X (XXX) females. Crow and colleagues later expanded the X chromosome hypothesis to include the possibility of a locus on the Y chromosome and, specifically, genes on X that escaped inactivation and are X-Y homologous loci. Some new information about possible risk loci on these chromosomes has come from the current large genetic consortia genome-wide association studies, suggesting that perhaps this hypothesis needs to be revisited for some schizophrenias. The following commentary reviews the early and more recent literature supporting or refuting this dormant hypothesis and emphasizes the possible candidate genes still of interest that could be explored in further studies.

This MiniReview describes the principle of mutation assays based on the endogenous Pig-a gene and summarizes results for two species of toxicological interest, mice and human beings. The work summarized here largely avoids rat-based studies, as are summarized elsewhere. The Pig-a gene mutation assay has emerged as a valuable tool for quantifying in vivo and in vitro mutational events. The Pig-a locus is located at the X-chromosome, giving the advantage that one inactivated allele can give rise to a mutated phenotype, detectable by multicolour flow cytometry. For in vivo studies, only minute blood volumes are required, making it easily incorporated into ongoing studies or experiments with limited biological materials. Low blood volumes also allow individuals to serve as their own controls, providing temporal information of the mutagenic process, and/or outcome of intervention. These characteristics make it a promising exposure marker. To date, the Pig-a gene mutation assay has been most commonly performed in rats, while reports regarding its usefulness in other species are accumulating. Besides its applicability to in vivo studies, it holds promise for genotoxicity testing using cultured cells, as shown in recent studies. In addition to safety assessment roles, it is becoming a valuable tool in basic research to identify mutagenic effects of different interventions or to understand implications of various gene defects by investigating modified mouse models or cell systems. Human blood-based assays are also being developed that may be able to identify genotoxic environmental exposures, treatment- and lifestyle-related factors or endogenous host factors that contribute to mutagenesis.

Induced pluripotent stem cells (iPSCs) allow researchers to make customized patient-derived cell lines by reprogramming noninvasively retrieved somatic cells. These cell lines have the potential to faithfully represent an individual\'s genetic background; therefore, in the absence of available human brain tissue from a living patient, these models have a significant advantage relative to other models of neurodevelopmental disease. When using human induced pluripotent stem cells (hiPSCs) to model X-linked developmental disorders or inherited conditions that undergo sex-specific modulation of penetrance (e.g., autism spectrum disorders), there are significant complexities in the course and status of X chromosome inactivation (XCI) that are crucial to consider in establishing the validity of cellular models. There are major gaps and inconsistencies in the existing literature regarding XCI status during the derivation and maintenance of hiPSCs and their differentiation into neurons. Here, we briefly describe the importance of the problem, review the findings and inconsistencies of the existing literature, delineate options for specifying XCI status in clonal populations, and develop recommendations for future studies.

Dosage compensation in Drosophila involves an approximately 2-fold increase in expression of the single X chromosome in males compared to the per gene expression in females with 2 X chromosomes. Two models have been considered for an explanation. One proposes that the male-specific lethal (MSL) complex that is associated with the male X chromosome brings histone modifiers to the sex chromosome to increase its expression. The other proposes that the inverse effect which results from genomic imbalance would tend to upregulate the genome approximately 2-fold, but the MSL complex sequesters histone modifiers from the autosomes to the X to mute this autosomal male-biased expression. On the X, the MSL complex must override the high level of resulting histone modifications to prevent overcompensation of the X chromosome. Each model is evaluated in terms of fitting classical genetic and recent molecular data. Potential paths toward resolving the models are suggested.