Patho Lecture- Chapter 5

What is a common measure of the effect of a specific risk factor?

Relative risk

Which statement is true regarding alcoholism? (Select all that apply.) -Alcoholism is more prevalent in females than males. -Individuals with the ALDH2*2 gene are less likely to become alcoholics. -Alcoholism clusters in families. -Alcoholism requires an environmental component.

-Individuals with the ALDH2*2 gene are less likely to become alcoholics. -Alcoholism clusters in families. -Alcoholism requires an environmental component. An allele of the ALDH2 gene (ALDH2*2) results in excessive accumulation of acetaldehyde and thus in facial flushing, nausea, palpitations, and lightheadedness. Because of these unpleasant effects, individuals who have the ALDH2*2 allele are much less likely to become alcoholics. More than 100 studies have shown that alcoholism clusters in families. Genes increase one's susceptibility to alcoholism, which means that alcoholism requires an environmental component, regardless of genetic constitution. Alcoholism is diagnosed in approximately 10% of adult males and 3% to 5% of adult females in the United States.

Explain a gene-environment interaction

A genetic predisposition may interact with an environmental-lifestyle factor to increase the risk of disease; this is called a gene-environment interaction

Which gene is linked with breast cancer? A. BRCA1 B. APC C. HLA II D. IDDM

A. BRCA1 BRCA1 is located on chromosome 17, and BRCA2 is located on chromosome 13. If women inherit these genes, then their lifetime risk of getting breast cancer increases by 50% to 80%. The APC gene is associated with colon cancer. Human leukocyte antigen (HLA) II is associated with diabetes. IDDM stands for insulin-dependent diabetes mellitus.

Which statement regarding coronary heart disease is true? A. It is the leading killer of Americans. B. Atherosclerosis causes widening of the blood vessels. C. CHD is more common in women. D. The relative risk for CHD does not increase with relatives affected.

A. It is the leading killer of Americans. Coronary heart disease is the leading killer of Americans. Narrowing of blood vessels occurs as a result of atherosclerosis. Men are more commonly affected. Relative risk increases when two or more relatives are affected before the age 55 years.

Which statement is true regarding Alzheimer disease? A. Alzheimer disease affects 40% of the population older than 65 years of age. B. Alzheimer disease is characterized by progressive dementia and memory loss. C. It has one gene locus. D. Antidiuretic hormone is a key factor.

B. Alzheimer disease is characterized by progressive dementia and memory loss. Alzheimer disease affects approximately 5% to 10% of the population, age 65 years and older. It is characterized by progressive dementia and memory loss. There are multiple gene loci with three being identified. ADH is aldehyde dehydrogenase, which is responsible for alcohol metabolism.

Which statement is true regarding the risks of developing a disease? A. Empiric risks are based on assumptions. B. Recurrence risk is higher if more than one family member is affected. C. An individual below the threshold of liability for a disease will have the disease. D. The recurrence risk for disease usually increases rapidly in more remotely related relatives.

B. Recurrence risk is higher if more than one family member is affected. Recurrence risk is higher if more than one family member is affected and usually decreases rapidly in more remotely related relatives. Empiric risks are based on observation. For diseases that have a threshold of liability, an individual usually does not have the disease below the threshold of liability.

Which statement describes a monozygotic twin? A. Twins who share very few traits B. Twins who share all traits C. Twins who form from double ovulation D. Twins whose rates vary among populations

B. Twins who share all traits Monozygotic twins divide from one embryo and actually share traits. They are natural clones. Twins from double ovulation are dizygotic and may not share traits. Monozygotic twins have the same rate across populations. Dizygotic or fraternal rates vary among populations.

Few traits are influenced only by genes or only by environment. Most are influenced by ____

Both It is incorrect to assume that the presence of a genetic component means that the course of a disease cannot be altered—most diseases have both genetic and environmental aspects

Which statement regarding hypertension is true? A. Systemic hypertension is observed in less than 5% of populations. B. Environmental factors do not cause hypertension. C. One of the most important factors affecting blood pressure is sodium intake. D. A 100% correlation exists among family members and blood pressure.

C. One of the most important factors affecting blood pressure is sodium intake. Sodium intake, obesity, decreased physical activity, and psychosocial stress are important environmental risk factors for obesity. Systemic hypertension affects approximately 25% to 30% of the population. Only a 20% to 40% correlation exists among family members.

Which statement is true regarding type II diabetes? A. Type II diabetes accounts for fewer than 10% of all cases of diabetes. B. Pancreatic insulin is not produced. C. These individuals experience insulin resistance. D. Type II diabetes is less common among obese persons.

C. These individuals experience insulin resistance. Type II diabetes is responsible for more than 90% of all cases of diabetes. Usually people who develop type II diabetes are older than 40 years of age and are obese. They produce insulin and have insulin resistance.

Which are congenital diseases in infants? (Select all that apply.) Cleft lip Clubfoot Hydrocephaly Obesity

Cleft lip- Correct Clubfoot- Correct Hydrocephaly- Correct Although people are born with factors that may cause obesity, infants are not born with this condition present. All of the other choices are traits that are present at birth.

What are congenital disease?

Congenital diseases are those present at birth. Most of these diseases are multifactorial in etiology

What type of twins are the result of a double ovulation followed by the fertilization of each egg by a different sperm?

Dizygotic twins

Concordant vs Discordant

If both members of a twin pair share a trait, they are said to be concordant. If they do not share the same trait, they are discordant.

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

Incidence rate

How is relative risk expressed?

It is expressed as a ratio of the incidence rate of the disease among individuals exposed to a risk factor divided by the incidence of the disease among individuals not exposed to a risk factor.

Explain multifactorial disease?

Many of the common adult diseases, such as hypertension, coronary heart disease, stroke, diabetes mellitus (types 1 and 2), and some cancers, are caused by complex genetic and environmental factors and are thus multifactorial diseases. For most multifactorial diseases, empirical risks (risks based on direct observation of data) have been derived. Multifactorial diseases in adults include coronary heart disease, hypertension, breast cancer, colon cancer, diabetes mellitus, obesity, AD, alcoholism, schizophrenia, and bipolar affective disorder. Studies of adopted children also are used to estimate the genetic contribution to a multifactorial trait. Several criteria are used to define multifactorial inheritance: (a) the recurrence risk becomes higher if more than one family member is affected; (b) if the expression of the disease in a proband is more severe, the recurrence risk is higher; (c) the recurrence risk is higher if the proband is of the less commonly affected sex; (d) the recurrence risk for the disease usually decreases rapidly in more remotely related relatives; and (e) if the prevalence of the disease in a population is f, the risk for offspring and siblings of probands is approximately √f

What type of twins originate when the developing embryo divides to form two separate but identical embryos?

Monozygotic twins

What is the definition of incidence rate?

Number of new cases of a disease reported during a specific period, divided by the number of individuals in the population The number of new cases of a disease reported during a specific period of time (typically 1 year), divided by the number of individuals in the population, is the incidence rate. The proportion of the population affected by a disease at a specific point in time is the prevalence rate. The effect of a specific risk factor is the relative risk. Polygenic genes cause variation.

Traits in which variation is thought to be caused by the combined effects of multiple genes are

Polygenic

What is the proportion of the population affected by a disease at a specific point in time?

Prevalence rate

What can be used to compare population variations in a disease frequency?

Prevalence rate and Incidence rate

What is a risk based on direct observation of data?

empirical risk

Term used when environmental factors also are believed to cause variation in the trait.

multifactorial trait