A child with 49 chromosomes. New York, NY [u. Share Share. J Clin Endocrinol Metab Clin Genet ;—
However, we do note that heterochromatic associations between the proximally located blocks of X heterochromatin can persist into prometaphase D ernburg et al. G ershenson ; Z itron and H awley ; Z hang and H awley Normal meiosis A is contrasted with failure of homologous chromosomes to separate in meiosis I B or of sister chromatids to separate in meiosis II C.
From Dorland's, As shown in the right column of Figure 4 and quantified in Table 3in oocytes in which X chromosomal crossing over was suppressed by inversion heterozygosity [either FM7a or In 1 dl ], the frequencies of XXY associations in late prophase stages 10—12 remained virtually unchanged from the frequencies observed in midprophase.
USA 30 : — PLOS Genetics. Indeed, the presence of the Y chromosome usually slightly increases X exchange, as measured among regular gametes, in XXY females with normal-sequence X chromosomes. Normally, there is a mechanism referred to as spindle checkpoint that checks whether the cell has correctly formed the spindle fibers and they have been specifically attached to the chromosomes.
Testosterone treatment may also improve behavior and learning disabilities in patients with Klinefelter syndrome. A prior study of one individual Ma et al. Subsequently, several groups reported that patients with the Klinefelter phenotype were often X-chromatin positive, and the presence of an extra X chromosome was hypothesized.
Hum Genet ;—
Genetic screening for gamete donors. No data are currently available regarding the recurrence risks for 47,XXY or other chromosomal variants of Klinefelter syndrome. It has been suggested that sperm aneuploidy should be employed as a routine screen before intracytoplasmic sperm injection treatment.
Oral testosterone undecenoate, 40 mg with meals three or four times daily, for long-term substitute treatment has also been recommended.