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Genetic diseases
Sem 1
| Question | Answer |
|---|---|
| What is Edward's syndrome? | Triosomy 18 |
| What are common features of Edward's syndrome? | -Affected individuals may have heart defects and abnormalities of other organs that develop before birth -small, abnormally shaped head -small jaw and mouth -clenched fist with overlapping fingers |
| How common is Edward's syndrome? | About 1/5000 live born infants, but most die before birth |
| What is Pateau syndrome a result of? | Triosomy 13 |
| What is Pateau syndrome associated with? | Severe intellectual disability and physical abnormalities in many parts of the body |
| How common is Pateau syndrome? | Occurs in about 1/1600 newborns |
| What percentage of infants with Pateau syndrome live past their first year? | Only 5-10% (Most die within the first few days, or weeks of life, many die in the uterus) |
| What are symptoms of Klinefelter's syndrome? | Usually results in infertile males of average intelligence. Decreased testosterone production. Sometimes in undescended testes, opening of urea on underside of penis or a micro-penis. Increased risk of developing breast cancer |
| What might decreased testosterone production result in with Klinefelter's syndrome? | Delayed or incomplete puberty, breast enlargement, and reduced facial and body hair |
| Which are commont traits of a female with triple X syndrome? | Sometimes infertile, but can have normal sexual development. They may have delayed development of motor skills, and behavioural and emotional difficulties. At an increased risk of learning disabilities. Often above average height with weak muscle tone |
| What causes Triple X syndrome? | A result of X-chromosome non-disjunction when the egg receives both X chromosomes. If the XX egg is fertilised by an X-bearing sperm, it results in triple X syndrome |
| What happens if an XX egg is fertilised by a Y-bearing sperm? | XXY karyotype; Klinefelter's syndrome |
| What is the karyotype of a female with triple X syndrome? | 47 XXX |
| How common is triple X syndrome? | Occurs in 1/1000 new-born girls |
| When are screening tests classed as screen positive for Down's Syndrome? | If the risk of having a term pregnancy with Down's is 1/150 or higher |
| What percentage of women carrying a Down's syndrome pregnancy will receive a screen positive result? | 84% |
| How many women in the screen positive group will actually be carrying a Down's syndrome pregnancy? | 1/10 |
| What are some common problems that individuals with Pateau syndrome have or develop? | Heart defects, brain and spinal cord abnormalities, very small/poorly developed eyes, extra fingers or toes, a cleft lip without a cleft palate and weak muscle tone. |
| What are some common traits of Down's syndrome? | Short stature, small nose and flat nasal bridge, small mouth, epicanthal fold in corner of eyes, broad hands with short fingers, simian crease, mental retardation, weak muscle tone, low set ears, enlarged protruding tongues,below average weight and height |
| What causes Down's syndrome? | Numerical abnormalities resulting in Triosomy 21. Can be caused by non-disjunction in meiosis 1 or meiosis 2, or in anaphase lag |
| Is Down's syndrome usually due to maternal or paternal origin? | 90% of cases are of maternal origin |
| What are common features of Turner syndrome? | Webbed neck, short stature, lack of sexual development, widely spread nipples |
| What is the karyotype of an individual with Turner syndrome? | 45XO |
| What causes Turner syndrome? | X chromosome non-disjunction when the egg cell doesn't receive an X-chromosome (both are discarded in first polar body), and it's fertilised by a x-bearing sperm |
| What would happen in an O egg was fertilised by a Y-bearing sperm? | Foetus would die |
| What percentage of individuals with Turner syndrome die before birth? | 97% |
Created by:
SandersE
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