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down syndrome- down syndrome- Presentation Transcript

  • Emre YARDIMCI Dönem 1 216015
  • Down Syndrome Trisomy 21 Not less, more.. 
  •  A short history and some basic info  Phsical charecteristics  Health complications  Genetics  The insedence  Risk factors for DS  Prognosis for DS  Treatments for DS  Cafe down at Ankara
  • John Langdon Down  Down syndrome, Down's syndrome, or trisomy 21 is a chromosomal disorder caused by the presence of all or part of an extra 21st chromosome. It is named after John Langdon Down, the British doctor who described the syndrome in 1866.
  • The disorder was identified as a chromosome 21 trisomy by Jérôme Lejeune in 1959.
  • The condition is characterized by a combination of major and minor differences in structure. Often Down syndrome is associated with some impairment of cognitive ability and physical growth as well as facial appearance.
  • Down syndrome in a baby can be identified with amniocentesis during pregnancy or at birth.
  • Individuals with Down syndrome tend to have a lower than average cognitive ability, often ranging from mild to moderate developmental disabilities.
  • A small number have severe to profound mental disability. The incidence of Down syndrome is estimated at 1 per 800 to 1,000 births, although these statistics are heavily influenced by the age of the mother.
  • Other factors may also play a role
  • Physical characteristics single transverse palmar crease upslanting palpebral fissures poor muscle tone protruding tongue a larger than normal space between the big and second toes
  • Health complications  Congenital heart defects  Leukemia  Gastrointestinal problems  Abnormal immune system  Eye disorders, hearing loss  Obstructive sleep apnea  Early Dementia
  • Common physical features
  • oblique eye fissures with epicanthic skin folds on the inner corner of the eyes
  • muscle hypotonia (poor muscle tone)
  •  a single palmar fold
  • a flat nasal bridge
  • a protruding tongue (due to small oral cavity, and an enlarged tongue near the tonsils)
  • white spots on the iris known as Brushfield spots
  • a larger than normal space between the big and second toes
  • Genetics  Trisomy 21  Mosaicism  Robertsonian translocation  Duplication of a portion of chromosome 21
  • Down syndrome is a chromosomal abnormality characterized by the presence of an extra copy of genetic material on the 21st chromosome, either in whole (trisomy 21) or part (such as due to translocations
  • The effects of the extra copy vary greatly among people, depending on the extent of the extra copy, genetic history, and pure chance. Down syndrome occurs in all human populations, and analogous effects have been found in other species such as chimpanzees and mice
  • The extra chromosomal material can come about in several distinct ways. A typical human karyotype is designated as 46,XX or 46,XY, indicating 46 chromosomes with an XX arrangement typical of females and 46 chromosomes with an XY arrangement typical of males
  • Trisomy 21 (47,XX,+21) is caused by a meiotic nondisjunction event.
  • With nondisjunction, a gamete (i.e., a sperm or egg cell) is produced with an extra copy of chromosome 21; the gamete thus has 24 chromosomes.
  • When combined with a normal gamete from the other parent, the embryo now has 47 chromosomes, with three copies of chromosome 21
  • Chromosomal nondisjunction
  • Trisomy 21 is the cause of approximately 95% of observed Down syndromes, with 88% coming from nondisjunction in the maternal gamete and 8% coming from nondisjunction in the paternal gamete
  • Mosaicism Trisomy 21 is usually caused by nondisjunction in the gametes prior to conception, and all cells in the body are affected. However, when some of the cells in the body are normal and other cells have trisomy 21, it is called mosaic Down syndrome (46,XX/47,XX,+21).
  •  This can occur in one of two ways: a nondisjunction event during an early cell division in a normal embryo leads to a fraction of the cells with trisomy 21; or a Down syndrome embryo undergoes nondisjunction and some of the cells in the embryo revert to the normal chromosomal arrangement.
  • • There is considerable variability in the fraction of trisomy 21, both as a whole and among tissues
  • This is the cause of 1– 2% of the observed Down syndromes.
  • Robertsonian translocation  The extra chromosome 21 material that causes Down syndrome may be due to a Robertsonian translocation in the karyotype of one of the parents. In this case, the long arm of chromosome 21 is attached to another chromosome, often chromosome 14 (45,XX, t(14;21q)) or itself (called an isochromosome, 45,XX, t(21q;21q))
  • Duplication of a portion of chromosome 21 Rarely, a region of chromosome 21 will undergo a duplication event This will lead to extra copies of some, but not all, of the genes on chromosome 21 (46,XX, dup(21q)).
  • The incidence The incidence of Down syndrome is estimated at one per 800 to one per 1000 births. In 2006, the Centers for Disease Control and Prevention estimated the rate as one per 733 live births in the United States (5429 new cases per year)
  • Risk factors for DS  Older maternal age  Older paternal age  Already having a child with DS  Carriers of the genetic translocation
  • About 90 percent of pregnant women who are given a Down syndrome diagnosis have chosen to have an abortion.
  • At maternal age 20 to 24, the probability is one in 1562; at age 35 to 39 the probability is one in 214, and above age 45 the probability is one in 19.
  • Maternal age influences the chances of conceiving a baby with Down syndrome
  • Prognosis for DS Adults with good self-help skills can be expected to live into . their 50s Those with poor self-help skills and live into their 40s. Their lifespan continues to increase
  • Down syndrome Seniors Mary Perry, aged 73 Peter Davison, died aged 68
  • Treatments for DS No medical cure Specialist team Care team Early intervention Countinuing self- help skills
  • Cafe down at Ankara  Waiters who are with down syndrome work at this cafe  Although that’s not new all over the world,it is the only and the first in Turkey
  • They dont give up so they are fulled- hopefull On the other hand,having motivational support makes the works better 
  • March 21  The first World Down Syndrome Day was held on 21 March 2006
  • Do me a favour! smile 
  • Best Regards!