Human Inherited Diseases: Overview Quiz

Human Inherited Diseases

• Diseases can be caused by genetic defects, leading to a disease phenotype
• There are two broad categories of diseases:
  • Single-gene (monogenic) defects
    • Caused by a single disease allele, dominant or recessive
    • Exhibit simple Mendelian inheritance patterns
  • Multi-gene (polygenic) defects
    • Caused by interactions of several genes
    • Exhibit complex, non-Mendelian inheritance patterns

Rare Diseases

• Defined as diseases with a prevalence of less than 1 in 2,000 individuals
• Often, but not always, governed by a single gene/locus
• Characterized by being chronic and life-threatening
• Often have an early onset, affecting children
• Estimated that 5,000-7,000 rare diseases exist
• Collectively, rare diseases are common: 6-8% of the population are affected
• Examples include:
  • Neurofibromatosis
  • Huntington’s disease
  • Phenylketonuria
  • Sickle-cell anemia (prevalence varies by region; 1/160,000 in EU, higher in Bahrain)

Common Diseases

• Commonly occurring in a population
• Often polygenic or multifactorial in nature
• Can be chronic, with onset later in life
• Nearly everyone is affected by a common disease at some point in their lives

Human Inherited Disease

• Human diseases are caused by genetic defects that result in a disease phenotype.

Two Broad Categories of Inherited Disease

• Single-gene (monogenic) defects: A single disease allele is inherited in a dominant or recessive manner, following a simple Mendelian pattern.
• Multi-gene (polygenic) defects: Interactions of several genes result in complex (non-Mendelian) inheritance patterns.

Rare Diseases

• Prevalence is less than 1 in 2000 people.
• Often, but not always, caused by a single gene.
• Chronic and life-threatening.
• Often present early in life, affecting children.
• Estimated 5,000-7,000 rare diseases exist, affecting 6-8% of the population.
• Examples: Neurofibromatosis, Huntington’s disease, Phenylketonuria, Sickle-cell anemia.

Common Diseases

• Occur commonly in a population.
• Polygenic or multifactorial in nature.
• Can be chronic.
• Onset is often later in life.
• Most people experience a common disease at some point in their lives.

Human Inherited Disease

• Some diseases are caused by DNA defects resulting in a disease phenotype.
• Two categories:
  • Single-gene (monogenic) defects: Single disease allele, dominant or recessive, simple Mendelian inheritance.
  • Multi-gene (polygenic) defects: Interactions of several genes, complex inheritance.

Rare Disease

• A disease with a prevalence of less than 1/2000.
• Often (but not always) governed by a single gene/locus.
• Often chronic and life-threatening.
• Often early onset - affecting children.
• Estimated 5,000-7,000 rare diseases exist.
• Collectively, rare diseases are common.
• Estimated 6-8% of the population are affected by a rare disease.
• Examples: Neurofibromatosis, Huntington's disease, Phenylketonuria, Sickle-cell anemia (prevalence varies by region: 1/160,000 in EU, higher in Bahrain).

Common Disease

• Occurs commonly in a population.
• Polygenic or multifactorial in nature.
• Can be chronic.
• Onset is often later in life.
• Pretty much everyone is affected by a common disease at some point in their life.