Unit 5 – Public HealthChronic Diseases

Chapter 11 – The Biomedical Basis of Chronic Diseases

Chronic DiseasesNow leading causes of death and disabilityMultiple causes – risk factorsLong period of onsetPossibility of secondary preventionImportance of animal models

Cardiovascular Disease, ctd.Total cholesterol level – low is better

Low density lipoprotein (LDL) – low is better High density lipotrotein (HDL) – high is better

Genetics are a major factorExercise lowers total cholesterol and increases HDLSmoking lowers HDLWidespread use of statins for secondary prevention

Cardiovascular DiseaseAtherosclerosisHeart disease and strokePlaque begins at an early age in U.S.American diet raises risk Diet, high blood pressure, diabetes, smoking interact to

cause injury of artery walls

Hypertension -- High Blood PressureImportant risk factor for cardiovascular diseaseEssential hypertension” – no known causeObesity, smoking, stress may be risk factorsRole of salt140/90 was considered borderline of high blood pressure;

guidelines have been lowered to 120/80. Secondary prevention is effective

CancerNot one disease, but many; each has different risk factors,

treatments, etc.Arises from mutations in DNAMutations caused by chemicals, viruses, radiationDiet and hormones play a roleTobacco use causes one-third of cancer deathsTesting chemicals for carcinogenicity is complex

DiabetesMajor cause of disabilityPrevalence is rising in US along with obesity Deficiency in the body’s ability to metabolize sugarType 1 diabetes – childhood onset; failure of insulin-

producing cells of pancreasType 2 diabetes – “adult onset;” insulin resistanceType 2 diabetes closely correlated with obesityTreatable, but need long-term monitoring; need good

access to medical care

Complications of DiabetesBlindnessKidney FailurePoor wound healingAmputations of the extremities

Other Chronic Disease of Public Health ImportanceAlzheimer’s disease and other dementiasArthritis

Unit 5 – Public HealthChronic Diseases

Chapter 12 – Genetic Diseases and Other Inborn Errors

Environmental TeratogensInfectious pathogens – syphilis, rubella, toxoplasmosisEnvironmental chemicals – e.g., mercuryDrugs – e.g., thalidomide, Accutane, hormonesAlcohol

Genetic DiseasesChromosomal abnormalities – e.g., Down syndromeMendelian genetics

Autosomal dominantAutosomal recessiveX-linked

May be caused by new mutationsSeverity of some genetic conditions may be affected by

environment -- e.g. anencephaly and spina bifidaFolic acid supplements can reduce risk

Genes influence susceptibility to diseases of adulthood

Newborn ScreeningTest drop of blood from newborns for metabolic

abnormalitiesAll newborns in US are screened for at least two

conditions: PKU and hypthyroidismStates vary in conditions screened for Most conditions are autosomal recessiveEarly diagnosis can prevent or reduce permanent

damageSome conditions are complicated to test for: e.g.

cystic fibrosis

Carrier Screening Screen for recessive genes in high-risk populationsTay-Sachs disease in Jews

Encouraged by Jewish leadersSickle cell disease in African Americans

Screening program in 1970s was misunderstood and poorly conducted

Prenatal DiagnosisOnly remedy may be abortionDown syndromeAnencephaly and spina bifida

Genomic MedicineHuman Genome ProjectMany potential benefitsMany dilemmasCancer genes: e.g. BRCA1 and BRCA2Targeted therapies

Guidelines for Genetic ScreeningNewborn screening only when benefits the newborn,

when can confirm diagnosis and when treatment and followup are available for infants

Carrier identification should be voluntary and confidential and include counseling

Prenatal diagnosis should be include education and counseling

All tests of high quality, evaluated by FDA; government oversight of laboratory proficiency

More education for the general public about genetics