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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.
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.
Unlike trisomy X, approximately half of women with tetrasomy X have no or incomplete pubertal development. Although in most cases tetrasomy X is significantly more severe than trisomy X, some cases of tetrasomy X are mild, and some cases of trisomy X severe. Like trisomy X, the full phenotypic range of tetrasomy X is unknown due to underdiagnosis.
Patau syndrome is a syndrome caused by a chromosomal abnormality, in which some or all of the cells of the body contain extra genetic material from chromosome 13.The extra genetic material disrupts normal development, causing multiple and complex organ defects.
Complete trisomy (having three copies of the entire chromosome) is lethal within days after conception. [13] Some partial deletions and partial duplications produce birth defects. The following diseases are some of those related to genes on chromosome 1 (which contains the most known genetic diseases of any human chromosome):
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.
Suspicion of a chromosome abnormality is typically raised due to the presence of developmental delays or birth defects. Diagnosis of distal 18q- is usually made from a blood sample. A routine chromosome analysis, or karyotype, is usually used to make the initial diagnosis, although it may also be made by microarray analysis. Increasingly ...
Cri du chat syndrome is a rare genetic disorder due to a partial chromosome deletion on chromosome 5. [1] Its name is a French term ("cat-cry" or "call of the cat") referring to the characteristic cat-like cry of affected children (sound sample ). [2] It was first described by Jérôme Lejeune in 1963. [3]