GENES

GENES, GENETIC DISEASE, CONGENITAL DISORDERS

I Background

A. DNA

1. gene

2. gene expression

B. Principles of Inheritance

C. Karyotypes

complete the karotyping activity online

When you have finished studying this material, you should be able to:

    - distinguish between gene, chromatin, chromosomes
    - draw a portion of a DNA molecule and label the complementary base pairings
    - distinguish between the processes of DNA replication, transcription, and translation
    - explain what is meant by “selective gene expression”
    - list three factors which contribute to “selective gene expression”
    - describe RNA splicing, hnRNA, and the difference between introns and exons
    - define sex chromosomes, autosomes, allele, genotype, phenotype
    - state what a karyotype is and how it is used
    - match chromosomes by length, centromere placement and banding patterns
    - use proper notation to identify the karyotype

II Genetic Disorders

A. Chromosome abnormalities

1. aneuploidy - aberrant number of chromosomes

a. Trisomy 21

b. Klinefelter syndrome (XXY)

c. Turner syndrome (X)

2. abnormal chromosome structure

a. Cri du Chat (deletion of short arm of #5)

B. Defective genes (small parts of chromosome)

1. single gene disorders - Mendelian inheritance pattern

a. autosomal dominant disorders

1. transmission

2. Marfan’s syndrome

3. von Willebrand’s disease

b. autosomal recessive disorders

1. transmission

2. PKU

3. Tay-Sachs disease

4. cystic fibrosis animation

c. sex-linked disorders

1. transmission

2. hemophilia

3. Duchenne muscular dystrophy

2. single gene - non-Mendelian inheritance pattern

a. triplet mutations

1. Fragile X

b. mitochondrial mutations

c. genomic imprinting

1. Prader-Willi

2. Angelman

3. significance

3. polygenic/multifactorial disorders

When you are finished studying the genetic disorders, you should be able to:
    - define genetic disorder
    - compare the impact of a chromosome abnormality vs a gene abnormality
    - define non-disjunction and possible causes
    - explain how non-disjunction and aneuploidy are related
    - list three examples of aneuploidy with their chromosome (karyotype) notation
    - describe the visible signs of Trisomy 21 and the possible internal effects
    - compare the impact of autosomal aneuploidy vs aneuploidy involving a sex chromosome
    - describe Klinefelter's syndrome, chromosomes and characteristics
    - describe Turner's syndrome, chromosomes and characteristics
    - list some causes of chromosome damage
    - describe Cri du Chat, chromosomes and characteristics
    - explain the usual result of a single gene defect
    - state the inheritance pattern of single gene traits and explain what this means
    - explain what is meant by autosomal dominant disorder
    - define reduced penetrance, expressivity
    - describe Marfan's Syndrome, chromosome and characteristics
    - describe the transmission of an autosomal recessive disorder
    - explain what is meant by an "inborn error of metabolism"
    - define consaguinity
    - compare and contrast PKU and Tay-Sachs disease
    - explain why males are more frequently affected by X-linked (sex-linked) recessive disorders
    - determine transmissions of sex-linked disorders to sons and daughters
    - compare and contrast hemophilia A, hemophilia B, and von Willibrand factor hemophilia
    - state the function of dystrophin
    - describe the pathogenesis of Duchenne muscular dystrophy and compare it to the pathogenesis of Becker's muscular dystrophy
    - identify creatine kinase and explain why it can be used to diagnose muscular dystrophy
    - list three categories of single gene disorders that do not follow Mendelian inheritance patterns
    - explain what is meant by a triplet mutation
    - describe Fragile X condition, chromosome, transmission, and characteristics
    - state the role of mitochondrial DNA and the effects of a mutation in this DNA
    - determine which areas of the body are most likely to be affected by defective mitochondrial DNA
    - explain what is meant by "genomic imprinting" and how Prader-Willi and Angelman syndromes revealed this effect

III   Congenital disorders (not genetic)

A. Teratology

1. timing

2. teratogens

a. thalidomide

b. alcohol

c. infectious agents (TORCH)

d. radiation

When you are finished studying the non-genetic congenital disorders, you should be able to:
    - explain what is meant by the fetal "matrix" and "predictive adaptive responses"
    - define teratology
    - list the three general types of teratogens
    - list several drug teratogens and explain the effects of one of them on the fetus
    - describe the mechanisms involved in alcohol teratogenesis
    - form an opinion about the FDA drug categories
    - state the meaning of TORCH
    - list the typical congenital disorders produced by the TORCH agents
    - identify the different stages of development and explain what is occurring generally during that stage
    - state the most vulnerable times during development and explain the reason for the vulnerability
    - define genetic predisposition
    - explain how slowing a developmental process can create a structural abnormality (cleft palate example)

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