28 Genetic hormonal deficiencies

Question 1

what causes disease

Answer 1

can be caused by genetic and/or environmental factors

Question 2

example of genetic factor that can cause disease

Answer 2

gene mutations, example of genetic disorder=colour blindness

Question 3

how do gene mutations cause disease

Answer 3

genes are regions of DNA that encode for production of proteins

gene mutations cause disease by disrupting the function or expression of cellular proteins

Question 4

what is DNA contained in

Answer 4

chromosomes

Question 5

what do chromosomes contain

Answer 5

genes and non coding DNA

Question 6

how many chromosomes does the haploid human genome have

Answer 6

23 –
22 autosomes and one seex chromosome (X or Y)

Question 7

where are haploid copies of human genome found

Answer 7

in egg and sperm cells

Question 8

what does the diploid human genome contain

Answer 8

46 chromosomes

Question 9

where are diploid human genomes found

Answer 9

in somatic cells

Question 10

how do cells have two copies of every gene

Answer 10

because they have two copies of each chromosome

(except X and Y in men)

Question 11

does every cell have the same set of genes

Answer 11

yes but they’re switched on/off depending on the cell

Question 12

different types of point mutations

Answer 12

• silent mutation
• nonsense
• missense (conservative nad non conservative)

Question 13

what are silent mutations

Answer 13

the mutation occurs but has no effect

Question 14

what are point mutations

Answer 14

changes a base to a stop codon

Question 15

what is a conservative missense mutation

Answer 15

the substitution of similar but not identical amino acids

Question 16

what is a non conservative missense mutation

Answer 16

occur when the new amino acid has different properties

Question 17

where do mutations occur

Answer 17

within the coding sequence

Question 18

how do mutations in non-coding DNA impact proteins

Answer 18

• may have no effect
• may affect protein expression

Question 19

what is an autosomal dominant disease

Answer 19

when a mutation in one allele causes the disease

the diseased gene is dominant - even if they have a second copt they will still have disease

Question 20

what percentage is there of passing an autosomal disease on to children

Answer 20

50%

Question 21

what do autosomal recessive diseases require

Answer 21

both alleles to carry the mutation

Question 22

what is the percentage of 2 parent carriers passing on an autosomal recessive mutation

Answer 22

25%

Question 23

what is a congenital disorder

Answer 23

a disorder that’s present at birth

Question 24

are genetic diseases always congenital

Answer 24

no eg huntington’s

Question 25

is hypothyroidism present at birth

Answer 25

yes

Question 26

what is hypothyroidism

Answer 26

low levels of thyroid hormones

Question 27

symptoms of hypothyroidism in infants

Answer 27

- jaundice - low body temp - poor muscle tone - excessive sleeping

Question 28

what can hypothyroidism lead to if untreated

Answer 28

- reduced growth - intellectual dysfunction

Question 29

causes of congenital hypothyroidism

Answer 29

genetic defects in - thyroglobulin gene (TG) - sodium-iodide symporter genes - TSH genes - TSH receptor genes

Question 30

what does TSH do

Answer 30

cause release of thyroid hormone

Question 31

treatment of congenital hypothyroidism

Answer 31

oral thyroxine (T4) given daily

Question 32

how are newborns tested

Answer 32

a heel prick procedure where blood is taken and measured for levels of T4 and TSH

Question 33

what is allan-hernon-dudley syndrome

Answer 33

rare disorder caused by loss of function mutation in MCT8 genes (x-linked)

Question 34

symptoms of allan-heron-dudley syndrome

Answer 34

- severe cognitive deficiency - most affected males never walk - most never speak

Question 35

what does MCT8 do

Answer 35

move thyroid hormone into the target cells

Question 36

how to treat Allan-hernon-dudley syndrome

Answer 36

diiodothyroproinoic acid (DITPA) has same effect as thyroxine but is membrane permeable

Question 37

what is isolated growth hormone deficiency

Answer 37

an autosomal recessive condition caused by a shortage or absence of growth hormone,, varies in severity

Question 38

what causes isolated growth hormone deficiency

Answer 38

most congenital cases are idiopathic but mutations have been identified in: - GH1 gene encoding growth hormone - GHRHR gene encoding growth hormone releasing hormone receptor

Question 39

does GH deficiency have an effect on prenatal growth

Answer 39

not a major one

Question 40

when is impaired length growth noted in isolated growth hormone deficiency

Answer 40

from a few months of age

Question 41

can affected children ever reach normal height with isolated growth hormone deficiency

Answer 41

yes if its treated early

Question 42

how to treat isolated growth hormone deficiency

Answer 42

with daily injections of GH need to be injections as its a protein hormone

Question 43

what type of hormones does the adrenal medulla secrete

Answer 43

amine hormones (80% epinephrine, 20% norepinephrine)

Question 44

what type of hormones does the adrenal cortex

Answer 44

steroid hormones (aldosterone, cortisol, adrenal androgens)

Question 45

when do adrenal androgens become detectible

Answer 45

from about 6 years old

Question 46

what is DHEAS converted to and in where

Answer 46

in peripheral tissues to more potent androgens, testosterone and dihydrotestosterone or to estradiol

Question 47

in MALES is the conversion of adrenal androgens more or less than the synthesis of active androgens by testes

Answer 47

the peripheral conversion of adrenal androgens is much less

Question 48

what % of active androgens does the adrenal gland contribute to in females

Answer 48

50% of the active androgens

Question 49

what is congenital adrenal hyperplasia (CAH)

Answer 49

an autosomal recessive disorder caused by a deficiency in enzymes needed to make cortisol and aldosterone

Question 50

what does congenital adrenal hyperplasia (CAH) cause

Answer 50

the body to produce more androgens which causes inappropriate or early development of male characteristics

Question 51

what does no feedback inhibition by cortisol cause (CAH)

Answer 51

ACTH levels rise which leads to a build up of cortisol precursors and enhanced production of androgens overstimulation leads to overgrowth of adrenal gland (hyperplasia)

Question 52

what are most cases of CAH caused by

Answer 52

mutations in the 21-hydroxylase gene

Question 53

what does mutation in 21-hydroxylase gene do

Answer 53

cause 21-hydroxylase deficiency which causes progesterone to be converted to 17-hydroxyprogesterone to adrenal androgens instead of progesterone to aldosterone and 17-hydroxyprogesterone to cortisol

Question 54

what deficiency do 90% of people with CAH have

Answer 54

21-hydroxylase deficiency

Question 55

what deficiency do 8% of people with CAH have

Answer 55

11-B-hydroxylase deficiency

Question 56

what can CAH cause (female genitalia)

Answer 56

- ambiguous genitalia - virilised genitalia

Question 57

treatments of CAH

Answer 57

- corticosteroids (eg oral hydrocortisone) to regulate blood glucose - mineralocorticoids (eg oral fludrocortisone) to regulate salt conc in blood - surgery to correct abnormal female genitalia (reduction clitoroplasty, construction of vaginal opening)