Dysmorphology

Question 1

What does dysmorphology normally refer to clinically?

Answer 1

Abnormal facial features

Question 2

What percentage of births are affected by congenital malformations?

Answer 2

2-3%

Question 3

What 3 things indicate that a congenital malformation is genetic?

Answer 3

1) Multiple malformations
2) Dysmorphic
3) Family history of similar problems

Question 4

22q11.2 deletion affects around 1/1500 births with a very variable phenotype, what are the features associated with it? 8

Answer 4

1) Learning difficulties (not severe retardation) ~70%
2) Cleft palate ~15%
3) Velopharyngeal insufficiency 32%
4) Congenital heart defects 75%
5) Hypocalcaemia
6) Seizures
7) Immune deficiency
8) Renal malformation

Question 5

Achondroplasia affects how many people and is caused by what kind of mutation?

Answer 5

1 in 20,000
Often new mutation
Autosomal dominant

Question 6

Increase in what increases the chance of a de novo mutation?

Answer 6

Paternal age

Question 7

Give the 3 clinical features associated with achondroplasia?

Answer 7

1) Short stature
2) Rhizomelic limb shortening
3) Foramen magnum compression/ hydrocephalus

Question 8

Beckwith-Wiedemann syndrome affects how many people and is associated with what 6 clinical features?

Answer 8

1 in 10,000

1) Large tongue
2) Ear pits/creases
3) Exomphalos
4) Hemihypertrophy
5) Neonatal hypocalcaemia
6) Increased risk of Wilms tumour (nephroblastoma)

Question 9

What is the most common chromosomal disorder and how many births does it affect?

Answer 9

Downs syndrome

1 in 800 live births

Question 10

What 10 clinical feature/complications are associated with Down syndrome?

Answer 10

1) Learning difficulties
2) Single palmar crease
3) Congenital heart disease
4) Alzheimer’s disease
5) Hypotonia in neonates
6) Cataracts
7) Hearing impairment
8) Hypothyroidism
9) Leukaemia
10) Atlanto-axial instability

Question 11

Is a single palmar crease present in individuals without Down syndrome?

Answer 11

Yes, present in other chromosomal disorders
Also present in the general population
Unilateral - 4%
Bilateral - 1%

Question 12

Kabuki syndrome occurs in how many births and is associated with what 7 defects?

Answer 12

1 in 30,000

1) Learning difficulties
2) Congenital heart disease 50%
3) Poor growth
4) Hearing impairment
5) Cleft palate
6) Premature breast development
7) Persistent fetal finger pads 96%

Question 13

In mosaicism hyper or hypo skin pigmentation in patches can occur, what pattern can this often occur in and what is required for diagnosis?

Answer 13

Pattern - follow Blaschko’s lines

Skin biopsy required for diagnosis

Question 14

Peutz-Jegher’s syndrome occurs in how many births and is associated with what 2 types of clinical features?

Answer 14

Occurs in

Question 15

Treacher-collins syndrome has a very variable phenotype, what are the 2 most common clinical features?

Answer 15

1) Cleft palate

2) Hearing impairment

Question 16

How many births does Treacher-collins syndrome occur and what is its mode of inheritance?

Answer 16

1 in 50,000

autosomal dominant

Question 17

Waardenburg syndrome occurs in how many births and is associated with what 6 clinical features?

Answer 17

1 in 250,000

1) Sensorineural hearing impairment
2) Iris heterochromia
3) Premature greying
4) White forelock
5) Areas of skin hypopigmentation
6) Congenital malformations (Hirschprungs/ VSD)

Question 18

What mutation causes William’s syndrome?

Answer 18

7q11 deletion

Question 19

William’s syndrome occurs in how many births and is associated with what 5 clinical features?

Answer 19

1 in 20,000
1) Learning difficulties
2) Cocktail part speech
Congenital heart disease
3) Supravalvular aortic stenosis
4) Peripheral pulmonary artery stenosis
5) Hypercalcaemia