2.15

Question 1

The same allele can have a different effect, depending on which parent it was

Answer 1

inherited from

Question 2

Prader-Willi syndrome is a genetic condition that affects

Answer 2

1 in every 12000-15000 people

Question 3

Prader-Willi affects both sexes and all

Answer 3

ethnic groups

Question 4

Prader-Willi is caused by

Answer 4

deletion of some of the genetic material on chromosome 15

Question 5

A child only develops Prader-Willi syndrome if the defective chromosome 15 is inherited from the

Answer 5

father

Question 6

12 main features of a child born with Prader-Willi:

Answer 6

• characteristic facial features (e.g. almond-shaped eyes, down-turned mouth, eyes close together, eyes pointing in different directions, thin upper lip)
• development delay including mild-moderate learning difficulties
• feeding problems in infancy leading to low weight gain
• underdevelopment of the sex organs and delayed puberty
• poor muscle tone
• rapid weight gain between 1-6years, can lead to serious obesity if no steps are taken to reduce this
• extreme hunger and obsession with food
• infants and children are usually happy and loving, with few behaviour problems, older children and adults may show behaviour problems, including temper tantrums and violent outbursts
• obsessive/compulsive behaviour (stealing and lying)
• usually short in stature, with small hands and feet

–often fair skin and light-coloured hair

-may have speech problems

Question 7

No cure for PWS but many of the symptoms can be

Answer 7

managed

Question 8

A key priority for PWS is to manage the person’s

Answer 8

weight

Question 9

Parents of children with PWS need to give the child a

Answer 9

balanced, low-energy diet with plenty of vitamins and minerals

Question 10

The use of growth hormone helps the child to

Answer 10

grow taller

gain more muscle mass

Question 11

Sex hormones may be used to

Answer 11

encourage more normal sexual development at puberty

Question 12

Advice is given about

Answer 12

behavioural management

Question 13

Speech and language therapy will help if there are

Answer 13

speech disorders

Question 14

Special educational programmes can assist the child to develop to their

Answer 14

full potential

Question 15

During gametogenesis certain genes in both sperm and oocytes are modified by the addition of

Answer 15

methyl (-CH3) groups

Question 16

The addition of methyl (-CH3) groups is called

Answer 16

epigenetic imprinting

Question 17

Epigenetics is used to describe

Answer 17

inherited changes in the DNA that do not involve a change in the DNA base sequence

Question 18

As a result of epigenetic imprinting, the chromosome is ‘labelled’ as

Answer 18

maternal or paternal and this means that they have different effects on the developing embryo

Question 19

The process must be

Answer 19

reversible - father to daughter = paternal, daughter to her child = maternal

Question 20

Epigenetic changes may be brought about by the environment, e.g. some heavy metals and pesticides can cause changes in DNA methylation - this also decreases as

Answer 20

cells age