Genetics and Disease

Question 1

what is aetiology and what is pathogenesis?

Answer 1

> aetiology = cause of the disease - ie genetic mutation, infection etc
pathogenesis = the mechanisms through which the aetiological factors interact with the body

Question 2

what is the difference between genetic, acquired, congenital and multifactorial diseases?

Answer 2

> genetic = abnormality in one or more genes transmitted from one generation to the next
acquired = due to environmental factors
congential = happened in the womb/from birth - so either genetic, or acquired via environmental factors in the womb before birth
multifctorial = both genetic and environmental factors both contribute to the disease - eg psychiatric conditions

Question 3

what is pleiotropy?

Answer 3

> when a single genetic trait codes for a protein that affects many differnt body systems in different way
some affected individuals may exhibit all features of a disease, and others fewer

Question 4

describe marfans syndrome

Answer 4

> a disease of a structurl protein fibrilin
autosomal dominant pattern of inheritance
skeletal abnormalities, long limbs etc
cardiovasular anomalies: aortic dissection
single gene disorder

Question 5

what is mosaicism?

Answer 5

> when some cells in the body differ in their genetic component from other cells in the body
some normal while others exhibit the disease state
- somatic mutation, germline mutation or a combination

Question 6

what genetic disorders are non-mendelian?

Answer 6

> chromosomal disorders - cytogenetics (numerical)
Mitochondrial disorders
polygenetic disorders

Question 7

describe cytogenetics

Answer 7

> numerical abnormalities in the chromosomes

• monosomy: affected individuals have 1 copy of sex chomosome instead of two - X turners syndrome. one copy of a autosomal chromosome is usually incompatible with life
• trisomy: three copies of a certain chromosome. 21, 18, 16 or 13 or sex

Question 8

Describe mitochondrial genetic defects

Answer 8

> defect in the mothers mitochondria is what gets passed onto the child, fathers mitochondria is lost in the flagella of sperm cell
mitochondrial disease is very debilitating - effects metabolism

Question 9

what are polygenic disorders?

Answer 9

> involved in pathogenesis of many common disorders such as:
- hypertension
- diabetes
- schizophrenia
- osteoporosis
two or more genes at a different loci contribute to the same trait/phenotype
each gene has an additive effect -> cumulative