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2021 May & June Cause

Genetic Disorders

Genetic disorders are diseases, which result from changes in the DNA sequence. The changes are called mutations and can affect one or multiple genes. These mutations are usually hereditary, meaning they are inherited from a parent. Sometimes these mutations happen randomly in individuals, but are usually associated with a certain environmental exposure (ie. smoking). 

 

It is important to note that not all mutations in DNA are harmful. DNA has lots of regions which are not encoded into proteins, nor provide any known function. Mutations in these regions would not affect a person in any way. In fact, the average person is estimated to carry 5-10 mutated genes in their cells. 

 

Video Lesson

Single-Gene Disorders

Single-gene disorders are disorders caused by a single gene mutation. The mutation can happen because:

  • it has been inherited by your parents

  • DNA had replicated incorrectly during cell division,

  • UV Radiation

  • Harmful chemicals

  • Viruses

examples of single gene disorders include:

  • Sickle Cell Anemia

  • Cystic Fibrosis

Chromosomal Disorders

Chromosomal disorders are disorders caused when an egg or sperm has a chromosomal abnormality. This can mean part of the chromosome can be deleted, duplicated, inversed, or moved. 

examples of chromosomal disorders include:

  • Down Syndrome

  • Turner's Syndrome

Complex Disorders

Complex disorders are disorders caused by many variables, most primarily family history and outside factors. 

examples of complex disorders include:

  • Heart Disease

  • Asthma

  • Diabetes

  • Parkinson Disease

Mitochondrial Genetic Inheritance Disorders

Mitochondrial disease can only be inherited from your mother. If your mother has a mitochondrial disorder, you have a 100% chance of also getting it. 

people suffering from Mitochondrial Genetic Inheritance Disorders have symptoms like

  • Weakness

  • Heart, liver and kidney diseases

  • Neurological problems

  • Respiratory problems

 

Single Gene Disorders

A single gene disorders are disorders caused by a single gene mutation. 

Background

  • Humans have pairs of chromosomes 

    • Each parent gives one chromosome (half of the chromosomal pair) to their offspring (kids) to make new pairs of chromosomes.

  • Chromosomes are full of genes

    • Mutations in those genes can cause genetic disorders

  • Genetic disorders can be dominant, recessive or sex-linked

    • Dominant genetic disorders cause disease when the mutation is present in at least one chromosome in the chromosomal pair

    • Recessive genetic disorders cause disease when the mutation is present in both of the chromosomes in the chromosomal pair  

    • Sex-linked genetic disorders can be dominant or recessive but only affect either the X or Y chromosome (sex-determining chromosome)

Cystic Fibrosis

  • Recessive

  • Mutation on the CFTR (cystic fibrosis conductance transmembrane regulator) gene

  • Causes secretions from cells to become thick and sticky (instead of being thin and slippery) which leads to clogging of the lungs and pancreas

Tay-Sachs

  • Recessive 

  • Mutation on the hexosaminidase A gene

  • Disorder that leads to the destruction of nerve cells in the brain and spinal cord resulting in paralysis, blindness and death

10,000

over

disorders caused by single gene mutation

1%

are affected by single gene disorders

about

Causes

  • Inherited by your parents through recessive or dominant inheritance patterns

  • DNA is duplicated incorrectly during cell division

  • UV radiation

  • Harmful chemicals 

  • Viruses 

Sickle Cell Anemia

  • Recessive

  • Mutation on the HBB (beta hemoglobin) gene

  • Makes red blood cells sickle-shaped, which clogs capillaries preventing blood circulation

Huntington Disease

  • Dominant

  • Mutation on the HTT (huntingtin) gene

  • Neurodegenerative disorder which leads to uncontrolled movements, deteriorating thinking ability, and emotional problems

 

Chromosomal Disorders

Chromosomal disorders are disorders caused when an egg or sperm has a chromosomal abnormality. This can mean part of the chromosome can be deleted, duplicated, inversed, or moved.

Background

  • Humans have 23 pairs of chromosomes, so 46 chromosomes total

    • Each parent gives 23 chromosomes so they child has 23 pairs of chromosomes

  • Chromosomal disorder can either be numerical or structural

    • Numerical disorders are caused by surplus or deficit of chromosomes

      • Monosomy - missing a chromosome in a pair

      • Trisomy - more than 2 chromosomes in a pair

Causes

  • When an egg or sperm has a chromosomal abnormality 

  • Abnormal division in the early stages of a fetus

  • Chromosomal breakage and incorrect rejoining 

  • Unbalanced chromosomal rearrangements

  • Deletions - part of the chromosome is deleted

  • Duplications - part of the chromosome is duplicated 

  • Translocations - part of chromosome is moved

  • Inversions - part of chromosome is inverted 

  • Rings - part of chromosome breaks and forms a ring

Down's Syndrome

  • Trisomy (3 copies) of chromosome 21

  • Results in learning difficulties and slowed development

Turner's Syndrome

  • Missing a sex chromosome, only born with one X chromosome

  • Has usually a shorter X chromosome than normal and is unable to have kids

Cri-Du-Chat

  • Deletion of chromosome 5p 

  • Babies have a high-pitched cry, low birth weight, and poor muscle tone

 

Complex Disorders

Complex disorders are disorders caused by many variables, most primarily family history and outside factors. 

Background

  • Complex disorders do not follow typical inheritance patterns, but tend to “run” in families

    • They do not obey recessive and dominant inheritance patterns

  • Genes play a role in a complex disorder but only results in a predisposition 

    • Environmental factors play the other role in the disorder

  • It is difficult to identify what genes are associated with the disorder

  • Caused by high blood pressure, high cholesterol and environmental factors/lifestyle choices (smoking, diet, medications)

Heart Disease

Asthma

  • Airway narrows and swells, and stresses (exercise, allergies, pathogens and medications) can cause an attack

Causes

  • Multifactorial inheritance 

    • Due to a balance between genetic and environmental factors

      • Genetic factors could be be mutations in one or more genes which could be inherited

      • Environmental factors include different stresses, chemicals, medications, smoking, diet, and alcohol 

  • These disorders tend to “run” in a family because they have similar genetics and are exposed to the same environmental factors

  • Alteration in a person’s lifestyle and environment can prevent the disorder

Diabetes

  • Genetics can cause prediabetes 

    • Too much sugar in blood but not enough to be classified as diabetes

  • Diet and exercise and other environmental factors can add to the genetic predisposition to cause the disorder

Parkinson Disease

  • Loss of nerve cells in the brain which are responsible for the production of dopamine

  • The factors involved in the progression of the disorder is unknown but some researchers think it could be linked to some pesticides/ herbicides

 

Mitochondrial Genetic Inheritance Disorders

Mitochondrial disease can only be inherited from your mother. If your mother has a mitochondrial disorder, you have a 100% chance of also getting it. 

Background

  • The mitochondria provides energy for a cell

    • They produce 90% of the energy in a human to function

    • They have their own separate DNA than the cell

  • Mitochondrial diseases are genetic, chronic, and inherited 

  • Disorders can result in not enough energy be produced to support the cell

  • Disorders can affect any part of a body 

  • Symptoms can be from mild to severe

  • It is difficult to diagnosis a mitochondrial disorder because it presents itself differently in each individual 

300

over

illnesses associated with a mitochondrial disorder

1 in every

4000-5000

people have mitochondrial disorder

Effects

  • Poor growth

  • Weakness

  • Heart, liver and kidney diseases

  • Neurological problems

  • Respiratory problems

  • Dementia

  • Learning disabilities 

 
 

Effects of Gene Therapy and Gene Modification

Postive Effects

  • good technique for diseases not researched yet

  • Wipe out genetic disease before they can begin and eliminate suffering for future generations

  • Is a 'medicine' for the future since it can control or eliminate hereditary diseases

  • Making diseased cells more evident to the immune system

  • Fixing mutated genes

  • Replacing mutated genes

Gene Therapy

Negative Effects

  • The patient's Immune system may react to the foreign vector

  • Other side effects depend on the type of vector used and how it is given

  • Genes could enter healthy cells, causing damage to them

  • Possibly cause damage to sperm or eggs

  • Damage could be passed on to future generations

  • Infection cause by the virus

  • possibility of causing a tumor 

  • Malignancy from retrovirally based gene therapies

  • Cause cancer or other damage

  • They can drive the production of so much of a protein that they can be harmful

  • Be transmitted to others or into the environment

Positive Effects

Gene Modification

  • We could get rid of hereditary disease

  • Every child would have a chance to be born healthy

  • This technology could eliminate fertility issues for couples

  • There could be mental health benefits to consider with human genetic engineering

Negative Effects

  • It does not eliminate the risk of a mistake happening
    - might create miscarriages or birth defects

  • Could increase the risk of allergies: women who are pregnant and eating GMO foods could endanger offspring by altering gene expression

Career Panel With Dr.Boone

 
 
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Organization: Genetic Disease Foundation

The Genetic Disease Foundation (GDF) is a non-profit 501c(3) organization established in 1997 by patients and families affected by genetic disorders. The Foundation’s mission is to support research, education and the prevention of genetic diseases.