Genetic Disorders Flashcards
1
Q
genetic terms pt1
A
- gene is a sequence of DNA that codes for a particular polypeptide
- allele is a different form of gene
- phenotype is an organism’s physical appearance, or visible traits
- genotype is the genetic makeup of an organism
- heterozygous is an organism that has two different alleles for a tait
- homozygous means two alleles are the same
- domniant is an allele that is always expressed
- recessive is only expressed in the homozoygous state
2
Q
genetic terms pt2
A
- sex linkage is the presence of a gene on a sex chromosomes
- carrier means one of the two alleles are carried by this person is the receive allele for a disorders/diseases
- affected/ sufferer - Disease phenotype
- non affected/ non-sufferer- non diseased phenotype
- genetic diagram shows the possible genes of offspring
- A punnet square shows all the possible outcomes of a genetic cross familal pedigrees can be used to record the inheritance of genetic disorders in a family tree.
- haemophilia is a sex-linked inheritable disease characterised by loss on impairement of the normal clotting ability of blood so that a minor would may result in fatal bleeding.
- weakness of genetic pedigree diagrams;——> diagram does not definitively show who are the carriers, it assumes the reporting of family lines is accurate, Other methods such as genetic screeening would give a definite result.
3
Q
what is cystic fibrosis, the symptoms and the causes
A
- cystic fibrosis is caused by recessive allele
- mucus becomes thicker and sticker and build-up in some internal organs leading to multiple pleiotropic( when one gene influences two or more seemingly unrelated phenotypic traits) effect,abnormal absorption of nutrients in the small intestine, chronic bronchitis
- mutation of CFTR gene on chromosomes 7 causes chloride ions channels to not function so CL- cannot pass out of the cell.
4
Q
what is huntington’s disease, the symptoms and the causes
A
- huntington’s is caused by dominant allele
- A gene affecting neurological function is defective, meaning a lack of neurotransmitter called GABA.
- tremors, clumsiness, memory loss, inability to concentate, ,ood changes
5
Q
what is haemophillia , the symptoms and the causes
A
- haemophillia is caused by sex linked recessive allele
- bleeding of the joints- gingival bleeding, unable to form clots at wounds
- lack of blood clotting factors or low number of blood clotting factors
6
Q
what is down’s syndrome , the symptoms, the risk factors and diagnosis
A
- A congential disorder caused by having an extra chromosome 21. Trisomy caused by chromosomes non- disjunction
- Physical growth, delays, intellectual disabillities, facial features, heart & circulatory problems, bad immune system
- advanced maternal age
- already having 1 child with DS
- being genetic carrier of genetic translocation - ultrasonography( in utero) & amniocentesis chorionic villus sample
7
Q
what is cancer, metatasis, benign and malignant tumour ?
A
- disorder in which some of the body’s cells lose the abillity to control growth and divide uncontrollably
- the spread of cancer cells beyond their original site
- an abnormal mass of cells that remains at its original site in the body
- an abnormal tissue mass that can spread into neighbouring tissue and to other parts of the body; a cancerous tumor
8
Q
what is protooncogenes, tumour suppressor genes (mutation), oncogene
A
- normal cellular genes that regulate cell division
- slow cell division
- cancer-causing genes that are formed due to mutations
- allows unregulated cellular growth.
9
Q
testing
A
- DNA sample sources comes from saliva, blood, semen and mucus
- limitation of DNA samples- chemicals used to prevent blood clotting when taking a DNA sample can affect the quality of DNA, may require multiple blood samples from more than one family member for comparison
10
Q
what are the advantages and disadvantages of genetic testing?
A
- increased knowledge about your risk of developing a disorder
- information to help make informed medical & lifestyle decisions
- can educate other family members
- earlier detection which increases the chance of survival
- testing may increase anxiety & stress
- testing does not eliminate a person’s risk
- cancer results in some cases may return inconclusive or uncertain
- increasing insurance premiums
- genetic discrimination
11
Q
genetic tests during pregnancy, advantages and disadvantages
A
- tests can be conducted whilst the foetus is in utero to detect genetic conditions. A blood test is carried out to assess the level of risk of the foetus having a genetic disorder, before amniocentesis or chorionic villus sampling takes place, as there is a small risk of miscarriage these tests.
- excellent screening tests for trisomies; low false positive rate gives potential to avoid an invasive test which carries a risk of miscarriage; Clarity of reported results low chance or high chance of aneuploidy
- may be a false negative or no result with a low-fetal fraction; may be a false positive with “vanishing” twin, maternal cancer or placental moscaicism
12
Q
what is chorionic villus sampling
A
- takes cells/DNA from the placenta
- which have same DNA as foetus
- allows earlier testing than amniocentesis
- allows for testing genetic/ chromosomal disorders
- test must be followed up by a blood test afterwards
- can tell the sex of the foetus earlier than observed with ultrasound
13
Q
what are the disadvantages of chorionic villus sampling and amniocentesis
A
- increase risk of miscarrige with both tests
- risk of infection in both
- risk of sensitsation/rhesus disease
- discomfort during & cramps after procedure
- not offered to all pregnant women
- women may be more likely to opt for testing if there is a history of genetic disorders in the family
- some people may be ethically opposed to prenatal testing
- prenatal tesing is optional and does not need to be accepted even if offered
- tests can’t check for every singel potential disorder
- Disorders tested for may depend on family history/ the lab that performs the tests
