Genetics 6

Question 1

What is the classification of obesity?

Answer 1

A BMI over 30.

Question 2

What is the classification of morbid obesity?

Answer 2

A BMI over 40.

Question 3

What is diabetes?

Answer 3

A constant state of hyperglycaemia due to either beta cell dysfunction or insulin resistance.

Question 4

What are the features of type 1 diabetes?

Answer 4

• Present at any age
• Autoimmune system attacks and destroys beta cells
• Diminished or completely absent endogenous beta cell function
• Treated with insulin replacement

Question 5

What are the features of type 2 diabetes?

Answer 5

• Onset is later

- Resistance to insulin, increases insulin production causing pancreatic exhaustion and eventual reduced secretion.

Question 6

What does monogenic diabetes mean?

Answer 6

Only one gene causing it.

Question 7

Examples of monogenic diabetes (3)

Answer 7

• MODY (maturity onset diabetes of the young)
• Mitochondrial diabetes
• Permanent neonatal diabetes

Question 8

What is permanent neonatal diabetes?

Answer 8

• Very rare (1 in 400,000 babies)
• Diabetes in the first 6 months of life
• Often weened off insulin

Question 9

What is mitochondrial diabetes?

Answer 9

• Maternally inherited via ovum
• Gives rise to maternally inherited diabetes and deafness (MIDD)
• MELAS
• Under diagnosed

Question 10

What is meant by polygenic diabetes?

Answer 10

A compilation of genetic changes that increase predisposition to developing diabetes.

Question 11

Examples of polygenic diabetes?

Answer 11

Type 1 and 2 diabetes

Question 12

How are SNPs for certain disorders discovered?

Answer 12

Genome-wide association studies (GWAS)

Question 13

What is HNF1-alpha?

Answer 13

A transcription factor that normally stimulates insulin production.

Question 14

What is the outcome of mutated HNF1-alpa?

Answer 14

In MODY there is haplo-deficiency of these factors so less insulin is produced.

Question 15

When do HNF1-alpha mutations become apparent?

Answer 15

Later in life when beta cell function begins to decline with age.

Question 16

How are HNF1-alpha mutations treated?

Answer 16

Best with sulfonylureas.

Question 17

What is glucokinase?

Answer 17

An enzyme that converts glucose into glucose-6-phosphate in glycolysis, eventually leading to insulin secretion.

Question 18

What happens in the case of a glucokinase mutation?

Answer 18

Results in a higher set point at which insulin is secreted, so that individuals have a constant state of mild hyperglycaemia. Treatment is rarely needed.

Question 19

Whats the difference between a germ-line and somatic mutation?

Answer 19

Germ-line mutations occur in gametes and can be passed onto offspring (entire organism is affected) whereas somatic mutations occur in a single cell body and cannot be inherited (only derivatives of cell are affected).

Question 20

What are the risks associated with increased paternal age?

Answer 20

• Autism
• Schizophrenia
• Rare birth defects
• Miscarriage
• Childhood acute lymphoblastic leukaemia

Question 21

What are the risks associated with increased maternal age?

Answer 21

• Down syndrome/chromosomal abnormalities

- Miscarriage