Applied Pathophysiology: Genetic and Developmental Disorders Flashcards

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Autosomal Dominant

Mutation located on the autosome

Inheritance of a mutation involving one dominant allele results in expression of the trait


Autosomal Recessive

Mutation located on the autosome

Inheritance of a mutation involving two recessive alleles results in expression of the trait

Inheritance of a mutation involving one recessive allele results in expression in carrier status for the trait.



Mutation located on the sex chromosomes

Gender difference in inheritance

  • Most are linked to the x chromosome
  • Males are more likely to be affected


Mitochondrial Gene Disorders

Related to energy production

Maternal inheritance

Not passed on by men



Polygenic Disorders

Multiple alleles at different chromosome locations affect phenotype

Complex interaction of multiple factors

Environmental influences (height)

Less predictable pattern

Monosomy (Turner Syndrome)

Trisomy (Down syndrome)



Alteration in chromosome number

During second meiotic division the chromosome doesn't split into the two daughter cells. One cell may have the two daughter chromosomes and the other may have none. When fertilized the father's sperm can add a third chromosome (trisomy) or the empty cell will receive only the father's chromosome (monosomy)


Congenital Disorders

Diseases or abnormalities that are present at birth


Congenital Disorders- Environmental factors

Chemicals, hormones, drugs, pathogens, environmental agents, nutrition, and intrauterine environment, ionizing radiation, maternal nutrition can have detrimental effects on anatomic and physiologic development


Congenital Disorders- Organogenesis

Development of organs between 3 and 8 weeks of gestation

Enviornmental factors can play a role in this


Congenital Disorders- Teratogens

Pathogens, drugs, alcohol, and environmental chemicals can cause damage to organs, physical and cognitive development, and spontaneous abortion


Congenital Disorders- Maternal Infection

TORCH- Toxoplasmosis, Other (Hepatitis), Rubella, Cytomegalovirus, Herpes


Fetal Alcohol Syndrome (FAS)

Caused by continued consumption of alcohol throughout pregnancy

Cognitive impairment, physical disability, growth deficit


Prenatal Screening and Diagnosis

Screens for chromosomal abnormalities and genetic risks through maternal blood for down syndrome or neural tube defects.

Ultrasound is used to determine any physical abnormalities

Fetal cells, percutaneous blood sampling, and amniocentesis


Treatment Strategies for Genetic and Development Disorders

Assess literacy level

Provide information about rates of risk

Promote ability to make informed decisions


Huntington Disease

Defect in Huntington gene on chromosome 4. Genetic mutation accumulates to toxic levels which destroys nerve cells and causes brain atrophy

The gene causes a triplet cytosine, adenine, guanine (CAG)

Degeneration of the basal ganglia and cortical regions of the brain

Progressive degenerative neurologic disorder with an autosomal dominant inheritance pattern


Huntington Disease Manifestations

Movement, emotional, and cognitive impairment

Dyskinesia- difficulty in performing voluntary movements

Huntington's Chorea- dancelike movements. Rapid, involuntary, nonrepetitive movement of the face, trunk and limbs

Personality changes, loss of memory, emotionally labile, antisocial, impulsive

Manifestations begin by mid 40's


Huntington Disease Diagnosis

Family history. A parent has a 50% chance of passing it on

Physical exam

Mental, cognitive, and emotional evaluation

Genetic testing

Blood testing for repetitive CAG

CT, MRI, PET scans


Huntington Disease Treatment

No cure

Drugs for movement and psychiatric disorders

Occupational, physical, and speech therapies

Nutrition management


Sickle Cell Disease

Single gene mutation with autosomal recessive inheritance

Homozygous: disease phenotype

Heterozygous: carrier

Point mutation leading to altered structure of the beta chain of hemoglobin in RBC

Sickled shape, known as hemoglobin S (HbS)

This is an ischemia disorder, NOT PAIN


Sickle Cell Disease Manifestations

Jaundice- RBC's breakdown and release bile

Anemia- RBC's are broken down in the spleen (hemolysis)

Pain- ischemia to the joints and chest during times of stress or low O2

Organ damage- ischemia and short lifespan of RBC's causes insufficient nutrients to organs


Related to the proportion of HbS in the circulation


Sickle Cell Disease Diagnosis

Genetic screening

Hemoglobin electrophoresis

Determine proportion of hemoglobin types

CBC, UA, AST, ALT, BUN, Creatinine


Sickle Cell Disease Treatment

Treatment depends on symptoms

Meds to prevent infection- vaccinations, flu, Hep...

Avoidance of extreme temperatures

Reduce stress- emotional and physical

Hydroxyurea (DMARD) helps promote production of Hemoglobin F to promote RBC's

Maintain hydration

Treat pain and infections

Mediport for easy IV access for frequent blood draws, and IV fluid replacement


Down Syndrome

Alteration in autosome number

Trisomy of chromosome 21

Result of nondisjuncture or inherited translocation


Down Syndrome Manifestations

Mental delay

Facial features

Cardiac defects

GI malformations

Visual and hearing impairment

Thyroid dysfunction

Prone to leukemias- ALL

Deeper cry


Down Syndrome Diagnosis

History and physical exam

Prenatal diagnosis: nuchal translucency, Quadruple test (serum alfa-fetoprotein, unconjugated estradiol, hCG hormone, inhibin A), amniocentesis, anatomic anomalies, fetal karyotype


Down Syndrome Treatment

Promotion of maximal independence and quality of life

Physical, speech, and occupational therapy

Treatment of associated congenital disorders


Turner Syndrome

Alteration in sex chromosome number. Monosomy of chromosome X

Results in decreased life expectancy. Diabetes and heart disease


Turner Syndrome Manifestations

Manifestations depend on the time of nondisjuncture

Short stature, gonadal failure: delayed puberty, infertility; cardiac and kidney abnormalities, skeletal and soft tissue abnormalities, hearing loss, learning difficulties and social problems


Turner Syndrome Diagnosis

History and physical exam

Prenatal screening: hygroma on the back of the neck (fluid filled sac or sacs that form from an error in development of lymphatic structures), edema, short femur, narrow aortic arch

Karyotype and genetic testing


Turner Syndrome Treatment

Treatments depend on the symptoms

Assistance in socialization

Hormonal therapy


Neural Tube Defects

Developmental disorders during embryonic development

Birth defects involving nervous system tissues

Spina bifida



Neural Tube Manifestations

Spina bifida- incomplete closure of vertebrae

  • without protrusion of meninges or spinal cord: spina bifida occulta
  • with protrusion of meninges: meningocele
  • With protrusion of meninges and spinal cord/nerve roots: myelomeningocele


Neural Tube Diagnosis

Physical exam

Prenatal screening: serum alpha-fetoprotein level, amniocentesis, ultrasound identification


Neural Tube Treatment

Spina bifida- surgical correction, supportive care

Prophylactic- FOLIC ACID!