About Down syndrome
The process that occurs in the cell is identified by a non-pairing of chromosomes so appropriate to the poles during anaphase called, so a gamete receives two chromosomes 21 and the other none.
As a way to honor Dr. John, Dr. Jerome anomaly baptized with the name of Down syndrome.
Anthropological Records show that the oldest case of Down syndrome date from the seventh century, a skull Saxon presenting structural changes often seen in children with Down syndrome. Some people believe that Down syndrome has been represented in the past carvings and pictographs.
The facial features of Oleic figurines carved by culture for nearly 3000 years were considered similar to those of people with Down syndrome.
No well-researched report on people with Down syndrome was published before the nineteenth century.
Types of Trilogy 21 or Down Syndrome There are 3 main types of chromosomal abnormalities or variations in Down syndrome.
Trilogy simple (standard) the person has 47 chromosomes in all cells (occurring in about 95% of cases of Down Syndrome).
The cause of simple trilogy of chromosome 21 is a chromosomal non-disjunction. translocation The extra chromosome pair 21 is "stuck" in another chromosome.
Nose case although individual has 46 chromosomes; it is carrying Down syndrome (about 3% of cases of Down syndrome).
The cases of mosaics may originate from mitotic no disjunction in the first divisions of a zygote standard. mosaic commits genetic change only part of the cell, or some cells have 46 chromosomes 47 and other (occurs in about 2% of cases Down Syndrome).
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