Paediatric Genetics

Question 1

what antenatal tests are done to look for genetic abnormalities in children?

Answer 1

antenatal scan:
12-40 weeks - nuchal folds etc
20 weeks - VSD and cleft palate

mother has blood tests

can also have:

• aminocentesis
• chorionic villus sample

Question 2

legal age limit for abortion in the UK?

Answer 2

24 weeks

Question 3

what are the different categories of genetic disorders?

Answer 3

chromosome abnormalities 
autosomal dominant 
autosomal recessive 
sex-linked 
.....

Question 4

what is trisomy 21 and what causes it

Answer 4

downs syndrome

maternal non disjunction in meiosis or translocation (if translocation you test the parents)

Question 5

what conditions are associated with down syndrome

Answer 5

congenital heart abnormalities - AVSD 
Hirschsprungs 
Coeliac disease 
Imperforate anus
Hypothyroidism
Hearing (glue ear) & vision problems 

learning difficulties

alzheimers dementia - early onset

Question 6

what is trisomy 13

Answer 6

Patau’s

Question 7

what is trisomy 18

Answer 7

Edwards

Question 8

what are the three survivable trisomy’s

Answer 8

13, 18, 21

Question 9

what is the likelihood of a child being affected by an autosomal dominant inherited condition?
and what conditions are carried this way?

Answer 9

1/2

Marfans, Huntington’s

Question 10

what is anticipation in autosomal dominant genetics?

Answer 10

with each generation the disease becomes earlier onset

Question 11

what is the likelihood of a child being affected by an autosomal recessive inherited condition?

what is the most common in UK?

what is the risk factor for having a baby with this?

Answer 11

1/4
although 1/2 will be carriers

CF and hemochromotosis

consanguinity

Question 12

what conditions are tested for in the newborn screening test?

Answer 12

CF
PKU
hypothyroidism
sickle cell

+ other metabolic disorders

Question 13

X linked conditions affect?

most important X linked conditions in the UK

Answer 13

males mostly!

but they can only get it from their mothers - only females are carriers

(because males only give their sons a Y chromosome), but all affects males will make their daughters will be carriers

duchennes
hemophilia

Question 14

what is XO?

Answer 14

turners

short stature,
webbed neck, puffy feet
- hypoplasia of the lymphatics

coarctation of the aorta –> can lead to heart failure –> nuchal thickness
or will see radio-femoral delay on examination

Question 15

what are the risk factors of neural tube defect

Answer 15

• mother not taking folic acid

- maternal diabetes

Question 16

who are mitochondrial disorders passed on from?

Answer 16

mothers - eggs are the only gametes big enough to carry mitochondria - sperm are too small

Question 17

what is prader-willi syndrome

Answer 17

neonatal hypotonia and poor feeing, moderate mental retardation, hyperphagia an obesity, small genitalia

caused by deletion in the paternally inherited

Question 18

what is angelmans syndrome

Answer 18

happy puppet - unprovoked laughing/clapping 
microcephaly 
seizures
mental retardation 
ataxic

Question 19

kaiser Fleischer rings, liver failure and chorea indicates?

how is it treated

Answer 19

recessive condition

copper

copper chelation therapy

Question 20

what mutation is most common in CF in the UK?

Answer 20

F508 mutation

Question 21

describe rett syndrome

Answer 21

…..google this

X linked recessive - only in girls?
There’s usually no family history of Rett syndrome, which means it isn’t passed on from one generation to the next. Almost all cases (over 99%) are spontaneous, with the mutation occurring randomly. This is known as a “de novo” mutation.

microcephaly

stage 1 - stagnation of development
stage 2 - regression of development
stage 3 - platau
stage 4 - deterioration of movement