Medical genetics and congenital disorders

Question 1

Name clinical features of trisomy 21

Answer 1

Hypotonia
Mental retardation
Brachycephaly
Flat facial profile
Upslanting eyes
Epicanthic folds
Flat nasal bridge
Small, low-set ears
Protruding tongue
Short stature
Brachydactyly
5th finger clinodactyly
Single palmar crease
Sandal gap
Congenital heart defect
Duodenal atresia

Question 2

How can you diagnose trisomy 21?

Answer 2

QF-PCR aneuploidy test

Karyotyping

Question 3

What is the cause of oculocutaneous albinism type II?

Answer 3

Mutation in P gene on chromosome 15 -> AR single gene disorder

Question 4

Name the clinical features of OCA2

Answer 4

Depigmented hair, skin and eyes
Nystagmus
Reduced visual acuity

Question 5

What should you screen OCA2 patients for?

Answer 5

Visual problems

Skin cancer

Question 6

Name examples of AD inheritance

Answer 6

Achondroplasia
NF type I
Marfan’s syndrome
Huntington’s disease

Question 7

Name examples of AR inheritance

Answer 7

Oculocutaneous albinism 
SMA
Sickle cell disease
Thalassemia
Cystic fibrosis
IEM

Question 8

Name examples of XLR inheritance

Answer 8

DMD
Haemophilia A
Haemophilia B
Fragile X syndrome

Question 9

What is the triplet repeat and normal repeat size in Huntington’s disease?

Answer 9

CAG

9-30

Question 10

What is the triplet repeat and normal repeat size in Friedrich’s ataxia?

Answer 10

GAA

8-33

Question 11

What is the triplet repeat and normal repeat size in Fragile X syndrome?

Answer 11

CGG

10-50

Question 12

Name examples of imprinting disorders

Answer 12

Prader-Willi syndrome
Angelman syndrome
Beckwith-Wiedemann syndrome

Question 13

How is mtDNA inherited?

Answer 13

Exclusively maternally inherited

Question 14

What can cause fetal akinesia sequence?

Answer 14

Fetal constraint

Single gene disorder (congenital MD)

Question 15

Name clinical features of neural tube defects

Answer 15

Anencephaly
Spina bifido
Encephalocoele

Question 16

What are complications of neural tube defects?

Answer 16

Death
Leg paralysis
Bladder/bowel incontinence
Hydrocephalus
Developmental delay

Question 17

Name clinical features of FAS

Answer 17

Growth retardation
Short palpebral fissues
Flat midface
Underdeveloped philtrum
Thin upper lip
Neurodevelopmental delay
Assoc congenital disorders

Question 18

What is deformation?

Answer 18

External force changes the shape of the normal tissues of the developing fetus

Question 19

What is disruption?

Answer 19

External agent destroys the normal tissues of a part of the developing fetus

Question 20

What is dysplasia?

Answer 20

Abnormal development of a single tissue type

Question 21

What is malformation?

Answer 21

Abnormal embyronic development

Question 22

What are the 5 questions a clinical faced with an individual with a birth defect/complex disorder should answer?

Answer 22

What is it?
What caused it?
What does it mean for the affected person?
Will it happen again?
Can it be prevented?

Question 23

What should non-blood samples for single gene testing always be submitted in?

Answer 23

Saline NOT formalin