Med Genomics 3

Question 1

autosomal dominant

Answer 1

reoccurence = 50% probability child will get affected or normal

vertical transmission

one dominant allele
seen in each Aa not aa

Question 2

causation of the same disease phenotype by mutations at different loci

Answer 2

locus heterogeneity

Question 3

genes that have more than one discernable effect on the body are said to be …

Answer 3

pleiotropic

Question 4

autosomal recessive

Answer 4

reoccurence = 25%

horizantal transmission

two affected parents will cause 100% affected

consanguinity seen

Question 5

differential activation of genes depending on the parent from why they are inherited

Answer 5

genomic imprinitng

inactive genes are called imprinted

long arm of chromosome 15 from

the father = prader willi syndrome (fat)

the mother = angelman syndrome (mental)

Question 6

anticipation and repeat expansion

Answer 6

in pedigree, as generation go on the disease displays an earlier age of onset and or more severe expression in more recent generations but will repeat and expand in further generations

Question 7

Disease associated with repeat expansion

• fragile x syndrome
• friedfreich ataxia
• huntingtons

Answer 7

fragile x - CGG (utr)

friedrich ataxia - GAA (intron)

huntingtons disease - CAG (exon)

Question 8

freidreich ataxia

Answer 8

GAA triplet - intron - site of expansion and affected sequence causes by nucleotide repeat mutation - autosomal recessive

Question 9

Trisomy 21

Answer 9

1 in 800 live births

DOWN SYNDROME

Question 10

95% of down syndrome is caused by what?

Answer 10

nondisjunction

95% of these are contributed by mother

75% occur during MEIOSIS 1

Question 11

Trisomy 18

Answer 11

edward syndrome

most common chromosome abnormality among still borns

Question 12

Trisomy 13

Answer 12

Patau syndrome

clefts, small eyes, polydactylyl

Question 13

Trisomy 16

Answer 13

most common at conception, never seen in a live birth

Question 14

Turner syndrome

Answer 14

karyotype 45x

females

short neck and stature

Question 15

Trisomy XXY

Answer 15

Karyotype 47xxy

Klinefelter syndrome

males

tall stature, long arms and legs

Question 16

harmful agents that could break chromosomes

Answer 16

clastogens

Question 17

interchange of genetic material among NONhomologous chromosomes

Answer 17

translocations

reciprocal - two breaks on different chromosomes with exchange of genetic material which result in duplication or deletion

robertsonian - long arms of two chromosomes fuse at centromeres to single chromosome

Question 18

fragile x syndrome

Answer 18

most common inherited cause of mental retardation - INHERITED - X exhibits breaks and gaps in tips of long arm

down sydnrome is chromosomal abnormality and not inherited gene mutation!

Question 19

when chromosomes divides perpendicular to its usual axis of division - resulting in chromosome that has two copies of one arm and no copies of the other

the genetic material is substantially altered so most are LETHAL

most isochromosomes observed at live births involve the X – have features of turner syndrome

Answer 19

isochromosomes

Question 20

trisomy 21 
45x 
47xxx 
47xxy - klinefelter 
47xyy

Answer 20

trisomy 21 - 1/800
45x - 1/5,000
47xxx - 1/1,000
47xxy - 1/1,000
47xyy - 1/1,000