Chapter 5: Genes, Environment, and Common Diseases

Question 0

Prevalence Rate

Answer 0

Proportion of the population affected by a disease at a specific point in time

Question 1

Incidence Rate

Answer 1

of new cases of a disease reported during a specific period (typically 1 year) divided by the number of individuals in the population

Question 2

Relative Risk

Answer 2

Incidence rate of the disease among individuals exposed to a risk factor
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Incidence rate of the disease among individuals NOT exposed to a risk factor

Question 3

Liability Distribution

Answer 3

Prediction of the probability of an individual having a specific disease based on exposure to genetic and environmental factors known to cause the disease

Question 4

Multifactorial Disorders

Answer 4

Result from hereditary and environmental factors, hereditary component is polygenic: individual involved genes follow Mendelian principles, many genes act together to influence the expressed trait

Question 5

Adoption studies

Answer 5

Gene-environment-lifestyle interaction, children born to parents who have a disease but are then subsequently adopted by parents lacking the disease are studied for the recurrence of the disease

Question 6

Recurrence Risks

Answer 6

Becomes higher if more than one family member is affected, expression of the disease is higher, proband is of the less commonly affected sex
Decreases rapidly in remotely related relatives

Question 7

Congenital Malformations

Answer 7

Congenital diseases are present at birth or shortly after birth, most congenital diseases are multifactorial, cleft lip and palate, spina bifida

Question 8

Hypertension

Answer 8

Risk factor for heart disease, stroke and kidney disease, 20-40% of blood pressure variations are genetic; this means that 60-80% are environmental
Causes of hypertension: sodium intake, lack of exercise, stress, obesity, smoking, and high-fat intake

Question 9

Breast Cancer

Answer 9

Affects 12% of American women who live to 85, if a woman had a first-degree relative with breast cancer, her risk doubles, recurrence risk increases if age of onset in the affected relative is early and if the cancer is bilateral, an autosomal dominant form(5%) has been linked to chromosomes 13 and 17, other genes are implicated

Question 10

Diabetes

Answer 10

Leading cause of blindness, heart disease and kidney failure

2 major types: type 1 (insulin dependent diabetes mellitus) and type 2 (non-insulin dependent diabetes mellitus)

Question 11

Type 1 Diabetes

Answer 11

Autoimmune destruction of insulin-producing beta cells in the pancreas (T cell activation and autoantibody production)
Onset before 40 years of age
Higher incidence with offspring of diabetic fathers
Recurrence risk .55 MZ twin concordance rate and 1-6% sibling recurrence

Question 12

Type 2 Diabetes

Answer 12

80-90% of all diabetes cases, neither HLA not autoantibodies commonly seen in type 2, person has insulin resistance or diminished insulin production, risk factors(high carbohydrate diet and obesity), recurrence risk(.90 MZ twin concordance rate) (10-15% sibling recurrence)

Question 13

Obesity

Answer 13

Body mass index>30, BMI=W/H^2 (weight in kg and height in meters) obesity is a substantial risk factor for heart disease, stroke, and type 2 diabetes, adoptive studies- body weights of adopted individuals correlated significantly with their natural parents’ body weights, twin studies-higher concordance in MZ twins than DZ twins

Question 14

Alcoholism

Answer 14

Risk is 3-5 times higher in individuals with an alcoholic parent, adoption studies-offspring of nonalcoholic parents, when reared by alcoholic parents, did not have an increased risk, twin studies concordance rates MZ: >60% DZ: <30%

Question 15

Schizophrenia

Answer 15

Severe emotional disorder characterized by delusions, hallucinations, and bizarre, withdrawn, or inappropriate behavior, recurrence risk among the offspring of one affected parent is 10 times higher than the general population, twin and adoption studies indicate that genetic factors are likely to be involved

Question 16

Bipolar Affective Disorder

Answer 16

Genetics, minimal environmental influence