Trisomy X is a sex chromosomal abnormality with a variable phenotype caused by the presence of an extra X chromosome in females (47,XXX instead of 46,XX). It is the most common female chromosomal abnormality, occurring in approximately 1 in 1000 female births. There is considerable variation in the phenotype, from asymptomatic and very mildly affected to significant physical and psychological f...

Chromosomal abnormalities are major causes of infertility, miscarriage and birth of handicapped progeny. In human live births, the prevalence of a chromosome aberration is ?0.5% and, of these, 0.1–0.3% correspond to structural chromosome rearrangements such as translocations, inversions, insertions and deletions .Our proband is an infant who had died 4 hours after birth due to a variety of abno...

nowadays, new advances in the use of cell free fetal dna (cffdna) in maternal plasma of pregnant women has provided the possibility of applying cffdna in prenatal diagnosis as a non-invasive method. in contrary to the risks of invasive methods that affect both mother and fetus, applying cffdna is proven to be highly effective with lower risk. one of the applications of prenatal diagnosis is fet...

Classical statistical genetics models of a quantitative trait depending on an autosomal gene indicate that father-to-daughter and mother-to-son correlations should be the same. If phenotypes are not sex-dependent, father-to-son and mother-to-daughter correlations also share this common value. On the other hand, if the gene is sex-linked, then the father-to-son correlation is zero. Such models d...

Canonical ancient sex chromosome pairs consist of a gene rich X (or Z) Chromosome and a male-limited (or female-limited) Y (or W) Chromosome that is gene poor. In contrast to highly differentiated sex chromosomes, nascent sex chromosome pairs are homomorphic or very similar in sequence content. Nascent sex chromosomes can arise if an existing sex chromosome fuses to an autosome or an autosome a...

Sex chromosomes in crane-fly spermatocytes move polewards at anaphase after the autosomes have reached the poles. In Nephrotoma abbreviate the sex chromosomes are 8um long by 3*5 jitm wide and have two orientations when they move: the long axis of the sex chromosome is either perpendicular or parallel to the spindle axis. We assume (1) that 'when a sex chromosome is perpendicular to the spindle...