Genetic and Pediatric Disease

Question 1

What is a homologous pair?

Answer 1

one maternal, one paternal

Question 2

Humans have _ pairs of chromosomes

Answer 2

23 (46 total)

Question 3

_ pairs of autosomes, _ pair of sex chromosomes

Answer 3

22, 1

Question 4

females X_, males X_

Answer 4

XX

XY

Question 5

permanent changes in the DNA structure

Answer 5

mutations

Question 6

substitution of a single nucleotide

Answer 6

point mutations (genome)

Question 7

insertion or deletion of 1 or 2 basepairs in an allele

Answer 7

frameshift (genome)

Question 8

aneuploidy results in _ mutations

Answer 8

chromosome

not an exact multiple of 23

Question 9

faulty disjunction during meiosis results in which type of mutation?

Answer 9

chromosome

Question 10

for chromosomal aberrations, most traits are lethal except for _ aberrations

Answer 10

sex chromosome

Question 11

for chromosomal aberrations, _ analysis is of primary importance

Answer 11

karyotype (pedigree is very difficult)

Question 12

in chromosomal mutations, there is usually no previous _, and _ is a frequent in survivors

Answer 12

family history of trait

mental retardation

Question 13

everyone is a carrier of _ deleterious genes

_% are familial

Answer 13

5-8

80-85

Question 14

3 patterns that single gene mutations can follow?

Answer 14

autosomal dominant
autosomal recessive
x-linked or sex-linked

Question 15

auto-dominant:
will manifest in _ state
genotypes are revealed by _
there are few _

Answer 15

heterozygous
phenotypes
carrier (possible)

Question 16

auto-dominant:
_% of offspring if 1 parent is affected
gender affected?
usually _ abnormality

Answer 16

50
girls and boys
structural

Question 17

reduced penetrance of auto-dominant may cause _
clinical features will vary due to reduced penetrance or _ expressivity
onset may be _

Answer 17

skipping of generations
variable
delayed

Question 18

autosomal recessive:

single largest category of _ disorders

Answer 18

mendelian

Question 19

autosomal recessive:

afflicted offspring usually have _ parents

Answer 19

phenotypically normal (carriers)

Question 20

autosomal recessive:
if both parents are carriers, risk to offspring is _%
if only 1 parent, _%

Answer 20

25

0, could be carrier

Question 21

autosomal recessive:

gender at risk?

Answer 21

female and males equally

Question 22

autosomal recessive:
afflictions are usually _
often _ error
does expressivity vary?

Answer 22

very severe
metabolic (don’t make specific enzyme)
no

Question 23

all sex-linked are _-linked

most people only have one active _ in most cells

Answer 23

X

X chromosome

Question 24

X-linked:
female carriers will pass condition on to offspring _%
can be _ expressed in _ females

Answer 24

50

partialy

Question 25

X-linked: | affected males will pass on _% to daughters and _% to males

Answer 25

100 (obligate carriers) | 0

Question 26

only 1 active X chromosome, the other X undergoes _ is inactive

Answer 26

heteropyknosis (happens randomly on 16th day)

Question 27

inactivation of the same X chrom persist in all cells that _ | not all precursor cells will _

Answer 27

derived from the same precursor cells | inactivate the same X

Question 28

X-linked: expressivity: _ difficult to diagnose at _ in general, the more X chroms, the _

Answer 28

subtle, chronic relating to sexual development at birth greater chance of mental retardation

Question 29

X-linked dominant: Do many conditions follow this line of transmission? Are there carriers? the genotype WILL show the phenotype

Answer 29

not many | no

Question 30

X-linked dominant: _% of sons and daughters from affected heterozygous females will be affected _% of sons and daughters from affected homozygous females will be affected _% of sons from affected males will be affected _% of daughters from affected males will be affected

Answer 30

50 100 0 100

Question 31

X-linked dominant: _analysis is easy _as many females as males affected in pedigree

Answer 31

pedigree | twice

Question 32

high proportion of ocular anomalies with what mode?

Answer 32

X-linked recessive

Question 33

X-linked recessive: practically all abnormal phenotypes in a pedigree are _ female carriers may sometimes have some expression depending on _

Answer 33

males | which X is expressed

Question 34

X-linked recessive: _% of affected males are carriers a women who is a carrier will pass trait on to _% of offspring

Answer 34

100 | 50

Question 35

fatherhood should be questioned if an x-linked recessive trait is expressed in a _ of a man who is without the trait

Answer 35

daughter

Question 36

multifactorial/polygenic traits: _ are very important how common? pedigree analysis?

Answer 36

environmental factors very common very difficult because so many genes involved

Question 37

multifactorial/polygenic traits: | continuous _ in expressivity

Answer 37

variation

Question 38

multifactorial/polygenic traits: | risk is correlated with _

Answer 38

degree of relationship of family members (more family affected, increased risk)

Question 39

down syndrome (trisomy 21) 1 in _ greater incidence associated with _ _> 40 years old

Answer 39

800 increasing maternal age alzheimer

Question 40

ocular symptoms of trisomy 21?

Answer 40

``` oblique palpebral fissures strabismus refractive errors epicanthal folds cataracts blepharitis ```

Question 41

marfan syndrome: a connective tissue disorder caused by a _ a _ disorder symptoms?

Answer 41

dominant allele familial long bones, tall, long fingers, scoliosis, depressed sternum, mitral valve prolapse

Question 42

ocular symptoms of marfan syndrome?

Answer 42

``` lens subluxation iris hypoplasia myopia ptosis strabismus ```

Question 43

turners syndrome: _ of x chromosome pretty _ appearance symptoms?

Answer 43

complete or partial monosomy (45,X) normal short, webbed neck, low posterior hairline, failure of secondary sexual characteristics

Question 44

ocular symptoms of turners syndrome?

Answer 44

prominant epicanthal folds, ptosis, strabismus, blue sclera, cataracts

Question 45

``` klinefelters syndrome: chromosomes? 1 in _ live male births rarely diagnosed before _ _ tests/penis low _ ```

Answer 45

``` XXY or more Xs 850 puberty small IQ ```