Many species groups, including mammals and many insects, determine sex using heteromorphic sex chromosomes. Diptera flies, which include the model Drosophila melanogaster, generally have XY sex chromosomes and a conserved karyotype consisting of six chromosomal arms (five large rods and a small dot), but superficially similar karyotypes may conceal the true extent of sex chromosome variation. H...

Background: Recurrent miscarriage (RM) is defined as two or more consecutive pregnancy losses before 20 weeks of gestation as an important clinical problem, with an incidence of 1-3% among couples wishing to have children. There are several factors in the etiology of recurrent miscarriage. One of the main genetic causes which involve in the pathogenesis of RM is balanced chromosomal rearrangeme...

X chromosome inactivation is most commonly studied in the context of female mammalian development, where it performs an essential role in dosage compensation. However, another form of X-inactivation takes place in the male, during spermatogenesis, as germ cells enter meiosis. This second form of X-inactivation, called meiotic sex chromosome inactivation (MSCI) has emerged as a novel paradigm fo...

Sticklebacks are small fish that inhabit fresh water and marine environments throughout the Northern Hemisphere. They are established models for the study of species evolution (speciation) and are more recent subjects for the study of chromosome rearrangements, as the chromosomes of the six species within the stickleback family differ in both number and morphology (shape/size). These difference...

It is well documented that female fertility is decreased with advanced maternal age due to chromosome abnormality in oocytes. Increased chromosome missegregation is mainly caused by centromeric cohesion reduction. Other factors such as weakened homologous recombination, improper spindle organization, spindle assembly checkpoint (SAC) malfunction, chromatin epigenetic changes, and extra-oocyte f...

contained a chromosome 7 abnormality (also mostly monosomy 7). Four of 11 patients with complex karyotype including aberrations of chromosome 7 showed cytogenetic responses (Figure 1; Table 1) compared with 2 responders of 9 patients with complex karyotype not containing a chromosome 7 abnormality. This high response rate in patients with chromosome 7 abnormalities is in stark contrast to the n...

BACKGROUND Preimplantation genetic diagnosis (PGD) has been stated to improve live birth rates compared with natural conception in couples with recurrent miscarriage (RM) carrying a structural chromosome abnormality. It is unclear to what extent this claim can be substantiated by evidence. A systematic review of the literature was performed on the reproductive outcome of these couples after nat...

BACKGROUND The annual number of parental karyotypes in cases of repeated miscarriage is increasing gradually in The Netherlands. The efficiency of offering parental karyotyping in couples with repeated miscarriage has not been evaluated before, especially not for the group with miscarriages at advanced maternal age. METHODS A historical cohort study and nested case-control study were conducte...

Chromosomal defects are relatively frequent in infertile men however, translocations between the Y chromosome and autosomes are rare and less than 40 cases of Y-autosome translocation have been reported. In particular, only three individuals has been described with a Y;21 translocation, up to now. We report on an additional case of an infertile man in whom a Y;21 translocation was associated wi...

EDITOR—Turner syndrome is one of the most common chromosomal abnormality syndromes aVecting 1 in 2500 liveborn females. The syndrome is characterised by short stature, gonadal dysgenesis, congenital heart disease, renal anomalies, and a variety of somatic features including neck webbing, cubitus valgus, short neck, and widely set nipples. Nearly half of the patients have a classical 45,X karyot...