Down's Syndrome

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Down syndrome (DS or DNS), also known as trisomy 21, is a genetic disorder caused by the presence of all or part of a third copy of chromosome 21. It is typically associated with physical growth delays, mild to moderate intellectual disability, and characteristic facial features.The average IQ of a young adult with Down syndrome is 50, equivalent to the mental ability of an 8- or 9-year-old child, but this can vary widely.

The parents of the affected individual are typically genetically normal. The probability increases from less than 0.1% in 20-year-old mothers to 3% in those age 45. The extra chromosome is believed to occur by chance, with no known behavioural activity or environmental factor that changes the probability.Down syndrome can be identified during pregnancy by prenatal screening followed by diagnostic testing or after birth by direct observation and genetic testing.Since the introduction of screening, pregnancies with the diagnosis are often terminated. Regular screening for health problems common in Down syndrome is recommended throughout the person's life.

There is no cure for Down syndrome.Education and proper care have been shown to improve quality of life. Some children with Down syndrome are educated in typical school classes, while others require more specialised education. Some individuals with Down syndrome graduate from high school, and a few attend post-secondary education.[16] In adulthood, about 20% in the United States do paid work in some capacity,with many requiring a sheltered work environment. Support in financial and legal matters is often needed. Life expectancy is around 50 to 60 years in the developed world with proper health care.
Down syndrome is caused by having three copies of the genes on chromosome 21, rather than the usual two.[2][62] The parents of the affected individual are typically genetically normal.[11] Those who have one child with Down syndrome have about a 1% risk of having a second child with the syndrome, if both parents are found to have normal karyotypes.[60]

The extra chromosome content can arise through several different ways. The most common cause (about 92–95% of cases) is a complete extra copy of chromosome 21, resulting in trisomy 21.
In 1.0 to 2.5% of cases, some of the cells in the body are normal and others have trisomy 21, known as mosaic Down syndrome.The other common mechanisms that can give rise to Down syndrome include: a Robertsonian translocation, isochromosome, or ring chromosome. These contain additional material from chromosome 21 and occur in about 2.5% of cases. An isochromosome results when the two long arms of a chromosome separate together rather than the long and short arm separating together during egg or sperm development.

Trisomy 21 (also known by the karyotype 47,XX,+21 for females and 47,XY,+21 for males)[65] is caused by a failure of the 21st chromosome to separate during egg or sperm development (nondisjunction).[61] As a result, a sperm or egg cell is produced with an extra copy of chromosome 21; this cell thus has 24 chromosomes. When combined with a normal cell from the other parent, the baby has 47 chromosomes, with three copies of chromosome 21.[2][61] About 88% of cases of trisomy 21 result from nonseparation of the chromosomes in the mother, 8% from non separation in the father, and 3% after the egg and sperm have merged.

Source : Wikipedia
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At 2:12 in the animation there is a mistake in the right chromosome, you wrote beneath the chromosome: 21q, 21 q, and it should be 21q, 14 q

abdahmad
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SIr WOW Your Explanation was brilliant understood wverything Love from pakistan.

hassanahmadsheikh
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Excellent and elaborated information. Thanks for the presentation.

sudheerpalaparthy
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Very good elicitation of concept... Thank you Soo much

aishasaleem
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This really helped me out! Thank you very much!

itsnao
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Can you make a video on symptoms of Down's syndrome? Unplumed nose 👃 and palpebral fissures, such symptoms are confusing to understand from the textbook, also in Turner's syndrome, I don't understand- peripheral lymphedema at Birth and streak ovaries. So it's a request, can you please upload seperate videos for the symptoms of these diseases, where you can explain these symptoms clearly 😅

sanikakadam
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اللهم صل على سيدنا محمد وعلى اله وصحبه وسلم تسليما كثيرا عدد خلقك وزنة عرشك ومداد كلماتك و عدد خلقك

alaaadel
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Fantastic explaination i was easily understand from tamilnadu

kaviyavd
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02:10 assalamualaikum sir, thanks for the nice lecture. One thing to be corrected I think, that is =
14q should be written instead of 21q

smodoctor
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Sir it would be better if u give some information regarding symptoms too
Otherwise nice video

Revival
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Bruh my parents didn’t tell my my little sister had Down syndrome until I secretly going out, cause I was doing a school project about chromosomes and I saw a picture of a baby with Down syndrome and they had the same facial features as my sister so basically saw my lil sister had the symptoms, soace between her 2 toes flat facial features and she didn’t t start walking until she was 2 and she can’t talk yet and she’s 3 and she’s delayed in many things.

kaceygrande
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My downs daughter is 26 she has no real physical issues but she does have the features and schizophrenia.

mlm
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This is so sad. It's really put me on a downer.

craig
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Please don't obscure slides by overwriting when u r speaking same language . This trick is distracting mind either to hear u or see what u over write . This practice can b helpful to these eho don't understand narrating it in different language . Thanks

AbdulMajid-uqsf
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There's a mistake at 2:18, 21q, 14q not both 21q

rrrrrrrrrrrf
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Do we call down syndrome a *congenital disease* ?

dentist
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What is the gamete of male with down syndrome ?

hawraa
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Pls suggest me my wife report's come trisomy 21 it's good or bad

IrfanKhan-efhg
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this was very clear and very nice, thank you!

taaptee
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Ask Scott Morrison he knows all about it!!!!

peterkirgan