A) All children will be affected
B) All children will be carriers
C) 50% of children will be affected
D) 50% of children will be carriers and 50% will be affected
E) 50% of boys will be affected and 50% of girls will be carriers
F) 50% of boys will be affected and all girls will be carriers
G) All girls will be carriers
H) All boys will be affected
I) 25% of children will be affected and 25% will be normal
J) 25% of children will be affected and 50% will be normal
K) 25% of children will be affected and 75% will be normal
L) 1 in 25 will be affected
M) 1 in 50 will be affected
N) 1 in 100 will be affected
O) 1 in 2000 will be affected
Instructions
For each scenario described below, choose the single most appropriate option from the above list of options. Each option may be used once, more than once, or not at all.
1) A healthy 20 year old woman is referred to the antenatal clinic at 10 weeks gestation. Her father has Huntington’s disease but she has declined screening. She wants to know the chances that her offspring will develop the disease.
2) A 19 year old woman with sickle cell disease is referred to the antenatal clinic at 10 weeks gestation. Her partner is a sickle cell carrier.
3) A 35 year old woman is referred to the antenatal clinic at 12 weeks gestation. Her father and brother are affected with Haemophilia A.
4) A 19 year old woman has a baby with Down’s syndrome due to t(21:21) translocation. The woman is found to have a t(21:21) balanced translocation and is planning another pregnancy
A) Maternal and paternal karyotype
B) Pre-implantation genetic diagnosis
C) Amniocentesis
D) Chorionic villus biopsy
E) Ultrasound for fetal sexing
F) Fetal blood sampling
G) Integrated test
H) Serum integrated test
I) Offer termination of pregnancy
J) Reassure
K) CT brain scan within 7 days of delivery
L) Repeat anomaly scan 1 week later
M) Maternal blood for DNA analysis
N) Detailed anomaly scan at 20 weeks
Instructions
For each scenario described below, choose the single most appropriate management from the above list of options. Each option may be used once, more than once, or not at all.
5) A 22 year old woman has been referred to the antenatal clinic at 20 weeks gestation because her anomaly scan showed an isolated choriod plexus cyst. She had screening for Downs syndrome which put her risk at 1 in 1850
6) A 35 year old woman is known to be a carrier of haemophilia A and has two affected children. She attends at 10 weeks gestation and wants to know whether or not the fetus is affected.
7) A 38 year old woman attends with a rash at 6 weeks gestation. The rash has been confirmed to be due to rubella infection.
Posted by A S.
1 - K correct
2 - D correct
3 - E correct
4 - A correct
5 - J correct
6 - D correct
7 - N wrong
dear sir,
why K for que 1? we dont know her status.
thanks.
mark.
Posted by Priti T.
I can guess why K is the answer.
Her risk of getting disease in AD[Autosomal dominent ]Disease is 1/2. And the risk further for her child is again half.So the cumulative risk is 1/2into 1/2=1/4.So 25%of the children affected n 75%normal.What do u thnk Dr Paul .
Thanks
Dr Priti
Posted by Maayka ..
1.K
2.C
3.E
4.A
5.J
6.D
7.I
Posted by PAUL A.
1) K: 25% of children will be affected and 75% will be normal
Autosomal dominant so there is a 50% chance the woman has inherited the defective gene. If she has, then there is a 50% chance of passing the gene on to any one of her children. So the probability of any child being affected is 50% x 50% = 25%, leaving 75% normal.
2) D - 50% of children will be carriers and 50% will be affected
Autosomal recessive. Woman is SS, partner is AS. Children will be AS, SS, AS, SS
3) This question was incorrectly worded and should have read: A 35 year old woman is referred to the antenatal clinic at 12 weeks gestation. Her father and son are affected with Haemophilia A. Please ignor the question / marking. We apologise for this
4) A - Monosomy 21 is not compatible with life so all children will have Down’s syndrome
5) J – Reassure. Isolated = no other abnormalities detected. Risk of Downs will be essentially unchanged. Choroid plexus cysts associated with trisomy 18 but in the absence of any other anomalies, the risk of this is low.
6) D – CVS – most appropriate diagnostic test at 10 weeks.
7) I – offer TOP based on gestation age at infection. Maternal infection at < 11 weeks - 90% of fetuses affected
