However, I have been unable to find a viable source for where this statistic came from. The incidence of calico or tortoiseshell in male cats is said to be 1 – 3,000. However, there is generally no reason to test for Klinefelter syndrome in male cats.įrequently asked questions How rare are calico and tortoiseshell cats? Calico or tortoiseshell coat pattern in a male catĬonfirmation of Klinefelter syndrome in humans is made by chromosomal analysis (karyotyping).Signs a male has Klinefelter syndrome can include: Most veterinarians and pet owners won’t be aware a cat has Klinefelter syndrome. How to diagnose Klinefelter syndrome in cats Unfortunately, there is scant data on the effects of Klinefelter syndrome in cats and most of the information available is from human studies. Humans with Klinefelter syndrome can have cognitive dysfunction, small testicles and penis, low sex drive, enlarged breast tissue, reduced muscle mass, decreased facial and body hair, increased belly fat and reduced bone mineral content. Examination of testicular tissue from one tortoiseshell cat found degeneration of the tubules, hyperplasia of the interstitial tissue, and complete loss of germ cells. In the case of cats with Klinefelter syndrome, the extra X chromosome is commonly associated with a failure of the testes to function properly, which explains why male calicos and tortoiseshell cats are usually sterile. The addition of the extra X chromosome means extra proteins that can affect the function of multiple systems within the kitten. The cat has two copies of each gene (one copy from each parent) which contains instructions that determine the kitten’s features, such as fur colour and pattern, eye colour, height etc. How does Klinefelter syndrome affect cats?Ĭhromosomes carry genes, which are made up of DNA. Possible outcomes Sperm cell (normally X or Y) If the egg or sperm carrying the extra X chromosome results in fertilisation, the kitten will have Klinefelter syndrome. However, if nondisjunction occurs, the egg or sperm will receive an extra copy of the X chromosome. Normally, the egg will receive one copy of the X chromosome and the sperm will receive one copy of the X or one copy of the Y chromosome. Why 19 and not 38? Gametes only contain 19 chromosomes so that when during fertilisation, the two cells combine to make the correct 38 chromosomes. The cells destined to be sperm or an egg undergo meiosis, in which the 38 chromosomes in the cell separate, and produce two new cells with 19 chromosomes each. Klinefelter syndrome is the result of a random nondisjunction error in cell division that happens during meiosis, the division of parent cells to produce gametes (sex cells) in the parent (male or female cat). Sex chromosomes with a slash, denote mosaics, which means the human (or animal) has a mix of two distinct cell types. XXXY, XXXXY, XXYY, XX/XXY, XY/XXY, XY/XXXY, XXXY/XXXXY, XXXYY, XXY/XX, XXY/XYY, XXY/XXXY, XXX/XXXY etc. The remaining 20% was made up of extra X and Y chromosomes in various abnormal combinations. This enabled chromosome maps to be made, and by 1959 it was possible to see that 80% of those termed as Klinefelters had three sex chromosomes instead of two. Counting chromosomesĪdvances in cytological techniques enabled Joe Hin Tjio and Albert Levan to determine the correct human chromosome count was 46, and not 48 as previously believed. He unselfishly allowed my name to come first in the list of authors because of the length of the title and the convenience of the eponym, it became known as Klinefelter’s syndrome. This is actually another of Dr Albright’s diseases. Eight additional patients with similar symptoms were encountered, with a range of clinical signs including low intelligence, high-pitched voices, gynecomastia and sterility.ĭr Klinefelter and his boss, Dr Albright published a paper in the Journal of Clinical Endocrinology in 1942, which describes the following. Hormone therapy failed to produce any notable results either way. His penis size and voice were normal for a male. Klinefelter syndrome was first described by Dr Harry Klinefelter in 1941, who examined an 18-year-old male who had gynecomastia (breast tissue), small testicles, and no facial hair. Down syndrome is the most well-known trisomy in humans that is caused by a third copy of chromosome 21. Klinefelter syndrome is a type of trisomy, which is a chromosomal condition characterised by an additional chromosome. Also known as XXY syndrome, Klinefelter syndrome (KS) is a sex chromosome condition that occurs when a male kitten is born with an extra X chromosome.
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