Disorders of Growth and Differentiation

Question 1

Name four different types of growth

Answer 1

Multiplicative
Auxetic
Accretionary
Combined pattern

Question 2

What is auxetic growth?

Answer 2

Growth in cell size as opposed to cell number

Question 3

What is accretionary growth?

Answer 3

A cell secretion to increase the volume of the extracellular spaces.

Question 4

What is a combined pattern of growth?

Answer 4

A mix of any of the other types of growth

Question 5

What are the different types of increased growth?

Answer 5

Hyperplasia - An increase in the amount of organic tissue that results from cell proliferation

Hypertrophy - An increase in mass of a cell, tissue, or organ without cellular proliferation

Combined hypertrophy and hyperplasia

Question 6

What is an example of physiological hypertrophy?

Answer 6

Athletes muscle

Question 7

What is an example of pathological hypertrophy?

Answer 7

Right ventricular hypertrophy

Abnormal enlargement of the cardiac muscle surrounding the right ventricle - when the heart has to work harder

Question 8

What is an example of physiological hyperplasia?

Answer 8

Adaptation to altitude

Psoriasis

Question 9

What is an example of hyperplasia in tissue repair?

Answer 9

• Angiogenesis
• Wound healing
• Liver regeneration
• Heart

Question 10

Give an example of physiological atrophy?

Answer 10

The thymus goes through regressive alterations with age

Ageing in general

Question 11

Give an example of pathological atrophy

Answer 11

• Muscle – fractures
• Nerves - paraplegics
• Blood supply – circulatory problems
• Pressure – bedsores
• Diet - anorexia

Question 12

What is Turner’s Syndrome?

Answer 12

Occurs in females with a missing X chromosome

Puberty will not occur or only partially occur
Females are shorter than average by 20 inches, only 5 with HRT
can live normal lives with regular chechup

Question 13

What is SHOX?

Answer 13

Short stature homeobox gene present on X and Y chromosomes

If mutated or one is missing it is associated with shortened stature syndrome

Question 14

Where is SHOX expressed?

Answer 14

SHOX is expressed in chondrocytes of the human growth plate

Question 15

What gene is linked to Down syndrome?

Answer 15

Trisomy 21

Question 16

What is Down syndrome associated with?

Answer 16

• Small stature
• Hypotonia
• Heart Defects
• Learning difficulties

Question 17

How may Down syndrome be identified?

Answer 17

Flattened nose and face, upward slanting eyes

Single palmar crease, short 5th finger that curves inward

Widely separated first and second toes + increased sole skin creases

Question 18

What is Beckwith-Wiedemann syndrome?

Answer 18

• Inheriting two copies of a chromosome from one (paternal) parent and none from the other is bad news
• Increased expression of IGF-II
• Decreased expression of H19
• Overgrowth in early childhood

Question 19

What is pituitary gigantism?

Answer 19

• Increased IGF-1
• Increased growth hormone
• Often from pituitary tumours
You grow real big

Question 20

What are some disproportionate alterations of skeletal growth?

Answer 20

• Achondroplasia (dominant allele)

* FGFR3

Question 21

What does loss of FGFR3 do?

Answer 21

Loss of FGFR3 increases growth
As
FGFR3 suppresses growth

Question 22

Where does mutation of FGFR3 have most effect?

Answer 22

Mutation of FGFR3 has most effect in chondrocytes

Question 23

What is metaplasia?

Answer 23

• Change of differentiated cell type
• Response altered cellular environment
• Often epithelial or mesenchymal cells

Question 24

Give an example of metaplasia

Answer 24

• Epithelium of trachea and bronchi in smokers

Question 25

What is dysplasia?

Answer 25

• Increased cell proliferation
• Atypical morphology
• Decreased differentiation
• Often Premalignant

Question 26

What is neoplasia?

Answer 26

• Abnormal uncoordinated excessive cell proliferation

* Persists after initiating stimulus withdrawn

Question 27

What are some disorders of differentiation and morphogenesis to do with anomalies of organogenesis?

Answer 27

– Agenesis
– Atresia
– Hypoplasia
– Ectopia/heterotopia 
– Maldifferentiation

Question 28

What cause congenital abnormalities in disorders of differentiation and morphogenesis?

Answer 28

Genetic or teratogenic(mutagen but for embryos kinda) causes

Question 29

What is agenesis?

Answer 29

The failure of an organ to develop during embryonic growth and development due to the absence of primordial tissue

Question 30

What is atresia?

Answer 30

A condition in which an orifice or passage in the body is closed or absent

Question 31

What is hypoplasia?

Answer 31

Underdevelopment or incomplete development of a tissue or organ. Although the term is not always used precisely, it properly refers to an inadequate or below-normal number of cells

Question 32

What is ectopia/heterotopia?

Answer 32

A displacement or malposition of an organ or other body part, which is then referred to as ectopic

Question 33

What is maldifferentiation?

Answer 33

• Failure of normal differentiation

* Persistence of primitive embryological features

Question 34

Provide some examples of atresia

Answer 34

Failure to develop a lumen
– Oesophageal atresia
– Duodenal atresia
– Imperforate anus

Failure to close
• Spina bida
• Cleft palate

Question 35

What is multicystic renal dysplasia (MRD)?

Answer 35

Multicystic renal dysplasia (MRD) is a malformative condition of the kidneys characterized by an abnormal metanephric differentiation and a renal cystogenesis

Question 36

What is Wilms’ Tumour?

Answer 36

• Developmental malignancy
Tumours can weigh up to 2kg
Can contain cartilage, bone and smooth muscle