Genetics

Question 1

25 year old with primary amenorrhoea, normal secondary sex characteristics, uterine & cervical aplasia. What is the genetic picture?

Primary amenorrhea with absent uterus, vagina ends in a blind pouch, normal breasts and scant pubic hair is seen with bilateral hernia

Answer 1

Mayer Rokitanski Kusher Hauser Syndrome
(booklet says this)

bilateral hernia = Androgen insensitivity syndrome

Question 2

At what number of weeks can CVS and amniocentesis be done?

Answer 2

CVS - from 11/40
Amniocentesis - from 15/40

Question 3

What is the inheritance of Achondroplasia

Answer 3

Autosomal dominant

Question 4

Diagnostic test for cystic fibrosis in blood

Answer 4

Chromosomal analysis

Question 5

Which test increases the number of copies of DNA?

Answer 5

PCR

Question 6

Quadruple test postive means

Answer 6

AFP decreased
Unconjugated E3 decreased
Bhcg increased
Inhibin A increased

Question 7

What hormone is deficient in congenital adrenal hyperplasia?

Answer 7

21 hydroxylase deficiency
Cortisol and androgen deficiency

Question 8

What are the findings on Down’s syndrome screening

Answer 8

AFP decreased
Unconjugated E3 decreased
Bhcg increased
Inhibin A increased

Question 9

Complete mole karyotype

Answer 9

46XX

Question 10

Mother and father homozygous for sickle cell: effect on children

Answer 10

Sickle cell

Question 11

Duchenne muscular dystrophy mode of inheritance

Answer 11

X linked recessive

Question 12

Sickle cell disease mode of inheritance

Answer 12

Autosomal recessive homozygous

Question 13

Trisomy 18 condition name

Answer 13

Edwards

Question 14

Partial mole genome

Answer 14

69 xxy

Triploidy
46 of paternal origin
23 of maternal origin

Question 15

Confined placental mosaicism

Answer 15

Abnormalities in the placental but not foetal tissues

Question 16

Mode of inheritance of Hungtons chorea

Answer 16

Autosomal dominant

Question 17

Mode of inheritance of Von willebrand

Answer 17

autosomal recessive

Question 18

mitochondrial chromosomes - inheritance

Answer 18

Inherited maternally only

Question 19

What is the 2nd common enzymatic deficiency after 21-OH CAH ?

Answer 19

11 beta-hydoxylase deficiency

Question 20

karyotype graph (47, XXY). What is the diagnosis ?

Answer 20

Klinefelters

Question 21

How many genes encoded in mitochondrial DNA?

Answer 21

37 genes

Question 22

Father has cystic fibrosis (rr), and the mother is normal (RR). What is the probability of having an affected child?

Answer 22

0%

Question 23

What is the name of a chromosome rearrangement that involves the transfer of genetic material between two non-homologous chromosomes?

Answer 23

Translocation
(reciprocal or robertsonian?)

Question 24

What is the difference between Robertsonian translocation and Reciprocal translocation?

Answer 24

Translocations:
Reciprocal - exchange segments of chromosome
Robertsonian - entire chromosome attaches to another at the centromere

Question 25

Does balanced translocation impact the genetic material quantity?

Answer 25

No loss of genetic material

Question 26

Does UN-blanaced translocation impact the genetic material quantity?

Answer 26

Increase of genetic material

Question 27

USS image 'bunch of grapes' What is the diagnosis and karyotype?

Answer 27

Complete mole 46 XX (NOT 46 XY)

Question 28

Trisomy 13

Answer 28

Patau

Question 29

Pedigree diagram: Carrier mother Unaffected father Affected son Mode of inheritance?

Answer 29

X linked recessive

Question 30

A woman is a carrier of CF and her partner is Caucasian with a rate of 1/25. What is the risk of the child having cystic fibrosis?

Answer 30

1% (1 in 4) x (1 in 25) 4x25 = 100 1 in 100 = 1% ?????

Question 31

Infertility case, Male 190 cm wt 60 kg, testicular volume 5 ml. What is the possible karyotype?

Answer 31

47XXY

Question 32

Rate of miscarriage in couples with balanced translocation?

Answer 32

2-5%?

Question 33

Case of a male with azoospermia and loss of smell (anosmia) diagnosis?

Answer 33

Kallman's Syndrome (hypogonadotrophic hypogonadism)

Question 34

Edwards syndrome in a male patient 46 or 47 XX or XY

Answer 34

47XY Trisomy 18

Question 35

Interpretation of downs screening results Age related risk; 1:1000MoM AFP; 1.05MoM β-hCG; 0.85 Test risk; 1:10000

Answer 35

Low risk for downs

Question 36

A woman is 8 weeks pregnant attends for genetic counseling as she worried about CF, her sister has a child with cystic fibrosis. She is a carrier and her partner is normal What is the risk of the child having cystic fibrosis?

Answer 36

0% Autosomal recessive Rr + RR = no chance of rr

Question 37

Mother has sickle cell disease married to sickle cell trait husband chance of baby to having disease?

Answer 37

50% Autosomal recessive rr + Rr = Rr/Rr/rr/rr

Question 38

Which chromosomes are capable of robertsonian translocations?

Answer 38

13, 14, 15, 21, 22

Question 39

Woman has a stillbirth (trisomy 13). Finds out she has a balanced translocation 13/14. What is the chance of having live baby with unbalanced translocation?

Answer 39

50% 1/4 - normal 1/4 - balanced 2/4 - unbalanced

Question 40

Primary amenorrhea, short stature, webbed neck

Answer 40

Turners

Question 41

Azoospermia, height 1.9m, small testes

Answer 41

Klinefelters

Question 42

Karyotype 46 XX, absent uterus

Answer 42

Rokitansky

Question 43

What is the mode of inheritance of BRCA1/2

Answer 43

Autosomal dominant

Question 44

What is the pattern of hormones in Klinefelter's ? Testosterone SHBG FSH/LH

Answer 44

Testosterone low SHBG high FSH/LH high

Question 45

Which two trisomies can be caused by robertsonian translocation?

Answer 45

Downs (21) and patau (13)

Question 46

Most common mutation in Lynch snydrome

Answer 46

MLH1 ? Think 'L' for Lynch (less so MSH2)

Question 47

What is the risk of ['accidental'] abortion associated with amniocentesis?

Answer 47

1%

Question 48

Which arm of the Y chromosome has the sex determining gene on it?

Answer 48

The short arm of the Y chromosome

Question 49

What is the karyotype of Edwards?

Answer 49

47XX +18 47XY +18

Question 50

What DNA band is stained during karyotyping

Answer 50

G banding

Question 51

Bilateral renal agenesis --> Oligohydramnios --> Compression: limb hypoplasia, low ears

Answer 51

Potter's syndrome

Question 52

What ~DNA issue causes Lynch syndrome

Answer 52

mutation of genes involved in DNA mismatch repair