disorders of development

Question 1

define: birth defect

Answer 1

cause of developmental anomalities during embryogenesis

Question 2

3 causes of brith defects?

Answer 2

genetics, environment, other/combination

Question 3

describe genetic causes of birth defects

Answer 3

single gene mutations or change in chromosome number (aneuploidy eg down syndrome)

Question 4

types of environmental casues of birth defects?

Answer 4

dietary insufficiencies and teratogens

Question 5

whats the dietary insufficiency?

Answer 5

folic acid -> decreased risk of neural tube defect

Question 6

define: teratogen

Answer 6

: environmental agents that come from outside the body (usually chemicals) that cause birth defects

Question 7

teratogens

Answer 7

_____ or _____ normal _______ ________

Question 8

how do teratogens go from being used by mum to affecting foetus?

Answer 8

cross the placenta

Question 9

effects of teratogens depend on:

Answer 9

Genotype of foetus and mother
Developmental stage at time of exposure (most sensitive in weeks 3-8)
Dose and duration

Question 10

example of multifactorial caused birth defect?

Answer 10

congential scoliosis

-abnormal lateral crvature of spine; due to gene and exacerbated by low oxygen

Question 11

define: penetrance

Answer 11

severity of defect

-influenced by many things eg. age, genetics

Question 12

2 examples of a birth defect?

Answer 12

achondroplasia and cleft palate

Question 13

describe achondroplasia

Answer 13

disease of bone formation resulting in short limbed dwarfism - normal trunk and short arms/legs, disporportionately large head;
Mutation on chromosome 4, FGFR3 gene (fibroblast growth factor receptor 3)

Question 14

define: syndrome

Answer 14

severe developmental anomalies coexisting

Question 15

causes of syndromes?

Answer 15

due to several genes on chromosome being affect or one gene having multiple effects when mutated (pleiotrophy)

Question 16

describe down syndrome genetics

Answer 16

trisomy 21 (aneuploidy) caused by non disjunction during meiosis
	Homologous chromosomes don’t separate at meiosis I
	Sister chromatids don’t separate at meiosis II

Question 17

how is down syndrome diagnosed

Answer 17

chromosome staining

Question 18

effects fo down syndrome?

Answer 18

cognitive problems, facila muscle changes, heart/gut anomalies

Question 19

describe thalidomide

Answer 19

o	Immunomodulatory drug (sedative) used to treat nausea and morning sickness in pregnant women
o	Causes widespread limb deformities in newborn babies
o	Phocomelia (malformed limbs)
o	Amelia (no limbs)

Question 20

describe lacohol

Answer 20

foetal alcohol syndrome - can occur for babies of women who consmed high levels of alcohol during pregnancy
o Low IQ, problems with memory/planning/decision making
o Growth deficiency, small nose, thin upper lip, rounded head, less developed brain – fewer neuronal connecitons from corpus callosum

Question 21

define: endocrine disruptors

Answer 21

exogenous chemicals that disrupt the endocrine system during development. they can mimic hormones, block its action and affect its production

Question 22

how are endocrine disrupotrs different from teratogens?

Answer 22

Tend to cause changes that are physiological effects that are seen in adult stages (unlike teratogens which are seen at birth)

Question 23

examples of endocrine disruptors?

Answer 23

diethylstilbestrol and xenoestrogens

Question 24

describe diethylstilbestrol

Answer 24

• thought to ease pregnancy and prevent miscarriage

- instead interferes with daughters repro system - hgher risk of infertility and pregnancy complications

Question 25

describe xenoestrogen

Answer 25

environmental chemcials that mimic estrogen

contribute to impaired testis function