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Complete trisomy 8 causes severe abnormalities on the developing fetus and can be a cause of miscarriage. [2] [3] Complete trisomy 8 is usually a gestational lethal condition, whereas trisomy 8 mosaicism is less severe and individuals with a low proportion of affected cells may exhibit a comparatively mild range of physical abnormalities and developmental delay. [4]
For example, out of the 16 binary strings of length 4, there are F 5 = 5 without an odd number of consecutive 1 s—they are 0000, 0011, 0110, 1100, 1111. Equivalently, the number of subsets S of {1, ..., n } without an odd number of consecutive integers is F n +1 .
Cat-eye syndrome (CES) or Schmid–Fraccaro syndrome is a rare condition caused by an abnormal extra chromosome, i.e. a small supernumerary marker chromosome. [2] This chromosome consists of the entire short arm and a small section of the long arm of chromosome 22.
Miscarriage, also known in medical terms as a spontaneous abortion, is the death and expulsion of an embryo or fetus before it can survive independently. [1] [4] The term miscarriage is sometimes used to refer to all forms of pregnancy loss and pregnancy with abortive outcomes before 20 weeks of gestation.
A breakage and reunion in the pericentric region of the p arm results in a dicentric isochromosome. [4] Some of the p arm can be found in this formation of i(Xq), but a majority of the genetic material on the p arm is lost so it is considered absent.
Human conditions due to monosomy: Turner syndrome – Females with Turner syndrome typically have one X chromosome instead of the usual two X chromosomes. Turner syndrome is the only full monosomy that is seen in humans — all other cases of full monosomy are lethal and the individual will not survive development.
The trisomy 21 karyotype figure shows the chromosomal arrangement, with the prominent extra chromosome 21. Trisomy 21 is the cause of approximately 95% of observed Down syndrome, with 88% coming from nondisjunction in the maternal gamete and 8% coming from nondisjunction in the paternal gamete. [4]
This results in an extra chromosome, making the haploid number 24 rather than 23. Fertilization of eggs or insemination by sperm that contain an extra chromosome results in trisomy, or three copies of a chromosome rather than two. [14] Trisomy 18 (47,XX,+18) is caused by a meiotic nondisjunction event.