Genetics

Question 1

What is the clinical presentation of Prader-Wili syndrome?

Answer 1

Hyperphagia, obesity, small hands and feet, hypogonadism

Question 2

What is the genetic cause of Prader-Willi syndrome?

Answer 2

4Mb deletion on chromosome 15q from PAPA

Question 3

What is the clinical presentation of Angelman syndrome?

Answer 3

spontaneous, uncontrolled laughter, ataxia, and severe intellectual disability?

Question 4

What is the genetic cause of Angelman syndrome?

Answer 4

a 4Mb deletion on chromosome 15q from MAMA

Question 5

What is uniparental disomy?

Answer 5

two copies of a chromosome inherited from one parent

Question 6

What is the clinical presentation of Beckwith-Wiedemann syndrome?

Answer 6

Large size for gestational age, large tongue, increased incidence of wilms tumor

Question 7

What is the genetic cause of Beckwith-Wiedemann syndrome?

Answer 7

Imprinting on chromsome 11p; contains IGF2 gene, with 2 copies from father (normally father provides one copy; none from mother)

Question 8

What is the clinical presentation and genetic cause of Silver-Russell syndrome

Answer 8

Growth retardation and short stature; deficient IGF2

Question 9

What are a major pro and con for a conventional gene karyotype?

Answer 9

PRO: Genome-wide; numerical & structural
CON: 5-10Mb resolution

Question 10

What are clinical presentations of Edward’s syndrome?

Answer 10

rocker-bottom feet, severe CNS impairment, horshoe kidneys, low and rotated ears

Question 11

What is the genetic cause of Edward’s syndrome?

Answer 11

Trisomy 18

Question 12

What are clinical presentations of Patau syndrome?

Answer 12

polydactyly, omphalocele, possibly holoprosencephaly or cleft palate

Question 13

What is the genetic cause of Patau syndrome?

Answer 13

trisomy 13

Question 14

What are clinical presentations of Cri-du-chat syndrome?

Answer 14

cry sounds like a cat, facial anomalies, severely low IQ (around 30)

Question 15

What is the genetic cause of Cri-du-chat syndrome?

Answer 15

deletion in chromsome 5p

Question 16

What are a major pro and con for FISH?

Answer 16

PRO: Resolution better than karyotype (smaller deletions & duplications detectable)
PRO: can be done on interphase chromosomes
CON: Limited to regions by tagged probes (NOT genome wide)

Question 17

What are a major pro and con of Comparative Genomic Hybridization?

Answer 17

PRO: Good at detecting deletions and duplications
CON: Done with metaphase chromosomes, resulotion not excellent

Question 18

What are major pros and cons of Cytogenetic Microarrays?

Answer 18

Question 19

How much DNA is shared by dizygotic twins?

Answer 19

50%

Question 20

A heritability score close to 1 indicated what?

Answer 20

Mostly genetically influenced

Question 21

How is heritability calculated?

Answer 21

Question 22

Understand the difference between fetal genetic testing

Answer 22

Question 23

What is an example of an indirect genetic test?

Answer 23

linked marker polymorphism; not exact, but can traces patterns of inheritance through family members

Question 24

Understand the differences between types of genetic tests

Answer 24

Question 25

Define incomplete penetrance:

Answer 25

Some individuals with a disease-predisposing genotype do NOT develop disease phenotype

Question 26

Which disease characterized by CAG repeats as well as age-dependent penetrance is notable for a progerssive loss of motor control (chorea)?

Answer 26

Huntington disease

Question 27

What is the major difference between incomplete penetrance and variable expression?

Answer 27

IP: binary; phenotype is presence or absent

VE: variability in severity of a disease or trait

Question 28

What type of genetic disease are Hemophilia A and Hemophilia B characterized as?

Answer 28

X-linked recessive

Question 29

What clotting factor deficiency is associated with Hemophilia A?

Answer 29

Factor VIII deficiency

Question 30

What clotting factor deficiency is associated with Hemophilia B?

Answer 30

Factor IX deficiency

Question 31

Proximal limb wasting with pseudohypertrophy presenting in distal limbs may indicate what X-linked recessive disease?

Answer 31

Duchenne muscular dystrophy

Question 32

Duchenne muscular dystrophy is typically caused by what types of mutations?

Answer 32

Frameshift (dystrophin is absent)

Question 33

Becker muscular dystrophy is typically caused by what types of mutations?

Answer 33

In-frame (dystrophin is present but abnormal)