MULTIFACTORIAL COMPLEX AND POLYGENIC TRAITS Flashcards

Question

WHAT DOES H=1 AND H=0 MEAN?

Answer 1

EG: heritability 1 = cystic fibrosis, sickle cell anaemia - heritability 0 = shot gun wound, light bulb in the buttocks

Answer 2

process by which congenital malformations are produced in an embryo or fetus

Answer 3

proliferation, distribution, migration and integration of cells, reduction of excessive parts (e.g. in-between fingers – first a mass of cells, then cells die (apoptosis) forming spaces between our fingers, giving them shape

Answer 4

- embryonal – organs and organ systems - fetal – organ components - perinatal – integrated systems (nervous, endocrine, immune) - postnatal - haematopoiesis, immune system

Answer 5

in the first 2 weeks a phase of “all or nothing” → if the embryo is damaged, development will stop -the more developed the embryo the less severer the potential disability

Answer 6

during later stages of development, mutations can leach on more easily – e.g. at the end of fetal stage mutations -> which can cause the formation of tumors, various syndromes

Answer 7

embryotoxic effect – death, malformation, growth retardation, disturbance of function

Answer 8

1. the genotype of mother and embryo, 2. type and dose of teratogen 3. ability of teratogens to go through placenta, 4. stage of pregnancy

Answer 9

THALIDOMIDE -> drug used in the treatment of common pregnancy problems (e.g. morning sickness) women (not all but some) which were using this drug gave birth to children with severe limb reduction such as missing limbs

Answer 10

yes - chemical teratogen -> excess of vitamin A and its analogues (vitamin A in the form of nutrition supplement part of a nutritional complex is not as risky as Vitamin A alone – only pure Vitamin A can be used to overdose) -other examples of chemical teratogens include warfarin (blocks vitamin K) and cytogenetics (stop plant growth) -other possibilities include: 1. antiepileptics → epileptics must change their medication ahead of time, before conceiving, as some antiepileptics are teratogenic – >treatment should not be stopped as if the mother gets an epileptic shock her baby may be at risk of hypoxia 2. psychopharmatics containing lithium 3. hormonal preparates, enzyme inhibitors, 4. Drugsdiazepam, salicylates, cocaine, LSD, cigarettes

Answer 11

– stage of morphological system development which the teratogen can damage

Answer 12

post critical period, where the main dangers have been overcome and the effects of teratogen is not as severe → depends of the type of teratogen and its dose – for all higher doses there are longer periods of sensitivity

Answer 13

effects proliferation, causes organ defects which are in the midst of development

Answer 14

require the presence of specific cell receptors; have a limited effect

Answer 15

Yes because severe teratogens are identified and eliminated, some traits disappear from the population and some are diagnosed in time, on the other side there is an increase in environmental pollution which causes different, less severe, birth defects → in conclusion the frequency is the same just that severe disorders are diminishing and less severe defects are increasing

Answer 16

-ionization radiation -hyperthermia (fever above 39°C lasting longer than 2 days can have teratogenic effect)

Answer 17

viruses - rubella, small pox, influenza bacteria - syphilis parasites - Toxoplasma gondii -> malaria

Answer 18

-nutrition - lack of 1. Ca, I, vit. D, folic acid malnutrition -disorders - phenylketonuria, diabetes

Answer 19

+/-2% -> most causes are unknown but can also be due to genetics, viruses and defects of mother

Answer 20

liability collectively describes all the genetic and environmental factors that contribute to the development of a multifactorial disorder.

Answer 21

At the point an individual accumulates a certain liability, they will be affected by the disorder. The level of liability at which this occurs is referred to as the threshold level. The liability required to exceed the threshold level is the same in all individuals; however, individuals with affected relatives (especially first degree relatives ) will have a higher chance of exceeding the threshold level and being affected. This is due to shared genetic and environmental factors. As a general rule, the later in life a multifactorial disorder develops, the more it is dependent on environmental factors (the lower the heritability). The pattern of multifactorial inheritance allows multifactorial disorders to be differentiated from autosomal disorders which they can resemble at a quick glance.