Chapter 7: Congenital and Genetic Disorders

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Chapter 7Congenital and Genetic Disorders

• Pathophysiology
• Ms. Harris

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Congenital/Genes

• Congenital defects or damage to a developing
  fetus that are present at birth
• Genetic abnormalities
• Malformation
• Chromosomal abnormalities
• Genes- are segments of DNA that code for a
  specific trait. DNA is what makes up chromosomes.

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Chromosomes

• Humans have 23 pairs. (23 from egg, 23 from
  sperm that join together to form the zygote)
• Karyotypes show all pairs
• 1-22 Autosomes
• 23rd pair sex chromosomes

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Normal female
Normal male
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Chromosomal Disorders

• Can be diagnosed by identifying abnormalities on
  a karyotype.
• Failure of chromosomes to separate in meiosis
  non-disjunction (result is either a monosomy or
  trisomy)
• Translocations, deletions of chromosomes can also
  occur

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• Can you spot the abnormality?

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Trisomy 21

• More commonly called Down Syndrome
• Causes mental retardation, shortened lifespan,
  oblique eye, smaller chin
• 1 in 1000 births

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• Can you spot the abnormality?

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Turners syndrome

• Malfunctioning ovaries, sterility, heart defects,
  short stature
• 1 in 2500 female births

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• Can you spot the abnormality?

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• Can you spot the abnormality?

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Congenital Defects, cont.

• Sometimes, just a single gene is affected.
• Sometimes, they are multifactorial

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Congenital Disorders, cont.

• Can be inherited or caused by teratogenic agents
• Things that cause damage to the fetus
• Smoke, alcohol, etc.

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Punnett Squares

• Used to predict chances for having a child with
  one of the following types of disorders
• Autosomal dominant, autosomal recessive,
  sex-linked dominant, sex-linked recessive

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Punnett Square Review

• Autosomal recessive(ex. Cystic fibrosis)
• What are the chances that an affected female and
  a normal (homozygous) male will have a child with
  cystic fibrosis?

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Punnett Square Practice

• Autosomal dominant (ex. Huntingtons)
• What is the probability that and affected
  (heterozygous) parent and a normal parent will
  have a child born with Huntingtons disease?

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Punnett Square Practice

• X- linked disorder (duchennes muscular
  dystrophy)
• What is the probability that a carrier female and
  a normal male will have a child born with MD?

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Pedigree Practice
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Multifactorial Disorders

• Lots of things factor into the expression of the
  disease
• Many genes
• Environmental factors
• Etc.

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Developmental Disorders

• Anomalies can be caused by exposure to
  teratogens.
• Mercury, alcohol, many chemicals
• First 2 months are the most critical because
  cells are differentiating (organogenesis)
• Cerebral Palsy

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Diagnostic Tools

• Amniocentesis for prenatal diagnosis
• Neonatal blood testing following birth
• Most hospitals make several tests mandatory

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Gene therapy

• Current Event Analysis
• Name 3 cause/effects from the article.
• Make a T-chart to list pros and cons of gene
  therapy. (think beyond the article!)