Ms. Smith's Biology: Period 1

Biology Resource Sites

How is it inherited?
What type of mutation occurs?
Characteristics of disease
Duchenne Muscular Dystrophy
  • It’s an inherited disorder that involves rapidly worsening muscle weakness.
  • It is a sex-linked disorder and is caused by a defective gene on the 23 or X chromosome.
  • Affected body fails to produce a functional muscle protein called dystrophin.
  • It’s passed down through the mother’s side usually onto their sons.
  • Males have a greater chance of inheriting this disorder while women are more likely to become carriers.
  • There is a fifty percent chance that the mother will pass it on to their sons and daughters, but daughters most likely become carriers because they did not inherit the trait from both parents.
  • It is the most common childhood disease and 1 out of every 3,600 male infants inherits it.
  • Duchenne Muscular Dystrophy is caused by a defective or alterted gene on the X chromosome.
  • this defect results in the failure to produce Dystrophin, a muscle protein.
  • Because it is a sex-linked disorder, it is more likely to strike males because they carry one X chromosome, unlike the female who only carries two X chromosomes.
  • when females do carry the disorder, they are mostly unaffected, but they have a 50 % chance of passing it on too their sons.
  • In males, the defect only needs to occur in the X chromosome once, but in females, the defect must occur in both X chromosomes to cause any harm.
  1. Fatigue
  2. Mental Retardation
  3. Muscle weakness in legs and pelvis. Also occurs in the arms and neck
  4. Difficulty with motor skills (ex. running, jumping, walking, and hopping.)
  5. Falling frequently
  6. Difficulty with standing up by him or herself
  7. General Weakness
  8. Lack of coordination
  9. Joint Contracture
  10. Walking disability
  11. Heel contracture
  12. Deformity of spine

· The symptoms for duchenne muscular dystrophy appear at the age of 3-6. By the age of 10, he or she needs braces to help him or her walk. By the age of 12, most patients are in a wheelchair.
  • There is no cure.
  • Physical Therapy-inactivity worsens disease
  • Use wheelchairs and walking braces
  • Spinal surgeries
  • Use breathing aids
  • Use steroids to slow down the symptoms of the disease.
Go to support groups to discuss their feelings and frustrations and to help each other.
Klinefelter's Syndrome
  • It is not inherited
  • It is most commonly caused by disjunction
  • The mutation that occurs is known as Nondisjunction. Nondisjunction is failure of separation of pairs of chromosomes during the process of Meiosis.
  • XXY males are alot weaker than the average baby

  • have less muscle and coordination control when toodlers

  • lack of testosterone causes: little or no facial and body hair, weaker bones, less body muscles, and broader hips than typical boys

  • lack of self confidence

  • infertility problems

  • have a chance of having breast cancer, lung disease, vein diseases, osteoporosis, extragonadal germ cell tumor, tooth decay, enlarged breasts, abnormal body proportions, depression, dyslexia, learning disabilities, and attention deficient hyperactivity disorder (ADHD)

  • have a harder time doing work that involves reading and writing

  • Educational services-helps with reading and writing
  • Speech, occupational, and physical therapy- can establish healthy sex lives, successful careers, and social relationships
  • Testosterone replacement-has the most impact during the first years of a patient's life. When the syndrome is diagnosed during adulthood, testosterone therapy is not proven to be as successful. also improves:

    • growth of body hair
    • appearance of muscles
    • concentration
    • mood and self esteem
    • energy and sex drive
    • increase strength
  • Seeing an infertility specialist- may be able to help the male get a woman pregnant
Turner's Syndrome
  • Most cases are not inherited, but a random event at the formation of reproductive cells causes a woman to only inherit one X chromosome
  • does not typically run in families
  • Turner syndrome occurs when females inherit only one X chromosome- their genotype is XO.

The characteristics of Turner’s syndrome can become apparent at birth and during infancy. They include:
· a wide/webbed neck
· a small jaw
· low set ears
· a low hairline at the back of the head
· drooping eyelids
· a broad chest with widely spaced nipples
· short hands
· arms that turn outward at the elbows
· fingernails turned upward
· being slightly smaller than average at birth
· swelled hands and feet at birth
· delayed growth.
In some individuals the characteristics of Turner’s syndrome don’t become apparent until they become older or reach puberty. The symptoms that occur in adolescents and older women include:
· no growth spurts
· a short height
· learning disabilities (often in subjects involving math)
· difficulty understanding other’s emotions and feelings
· not going through normal sexual changes that usually occur during puberty (due to ovarian failure that could have occurred in which little to no estrogen or other hormones are produced)
· a non-existent menstrual cycle (not due to pregnancy)
· the inability to conceive a child without a fertilization treatment
  • if caught early in life the first that would be started would be a weekly measured dossage of growth hormones called somatropin
    • used to increase height
    • should be started right when the disease is apparent(or by age of 4)
  • Ovarian hormone therapy
    • since mostly found in women once puberty starts(ages range from 12 to 15) patients are started on hormone therapy so that normal development of sexual parts can take place
    • helps to start puberty
  • Hormone replacement therapy
    • reduces chances of obtaining ovarian failure, osteoporosis,diabetes, and heart failure
    • also helps high blood pressure due to the size of the aorta or a kidney abnormality
  • Assisted reproduction
    • 50% of women who go through assisted reproduction have been reported to have become pregnant
      • This doesn't mean that the pregnancy is a sure deal. These women are still at a high risk of having a miscarriage, having twins, or their child being born with chromosomal abnormalities.
    • One way to achieve a pregnancy is through egg donors.
Cystic Fibrosis
  • People with Cystic Fibrosis have two malfunctioning copies.
  • Inherit the mutated gene one from each parent
  • The functioning copy overrules malfunctioning copy &that person does not carry cystic fibrosis
  • inherited metaboli disorder
  • Lies in Chromosome 7
  • 70% of mutations are a result from the deleting of three base pairs, which make the amino acid Phenylaline, from a CFTR's nucleotide sequence
  • CFTR stands for Cystic Fibrosis conductance regulator
  • Phenylaline is located in position 508 in the protein, thus causing the mutation to be called Delta F508
  • The deletion of Delta F508 is the most common cause of Cystic Fibrosis
  • Thick, sticky mucus blocking airways/channels
  • Causes damage to the respiratory system and chronic digestive system problems
  • Bacterial infections
  • Wheezing
  • Weight loss
  • Permanent lung damage
  • Scarring of tissue
  • Cysts in the lungs
  • No cure
  • No cure
  • Chest physical therapy
  • Exercise
  • Medicines/Antibiotics
  • Nutritional therapy
Sickle Cell Anemia
  • Mutation that causes is recessive
  • 2 carrier parents: 25% chance have 50% chance carry
  • 1 carrier 1 not:: 50%chance carry
  • Chromosome 11
  • HBB gene
  • Substitution Thymine instead of Adenine
  • Strokes
  • Swelling of hands and feet
  • Slower development and growth
  • Delay of puberty in children
  • Fatigue, paleness, and shortness of breath
  • Slower healing and increase in infections
  • Yellowing of skin, eyes, and mouths
  • no cure
  • treated with oral penicillin
  • infants born with fetal hemoglobin (HbF) hyfroxyurea
  • lifelong is blood transfusions
  • Future: bone marrow transplants
  • only donor is a healthy sibling
  • only 18% of people have a match.
Werner Syndrome
  • Inherited in an autosomal recessive pattern
  • Both copies of WRN gene in all cells are mutated
  • Both parents carry one copy of the mutated WRN gene (don't always show symptoms)
  • Mutation of WRN gene cause Werner syndrome
  • Werner protein
  • Cannot repair DNA
  • Problems in replication
  • Chromosome 8 position 12
  • Extreme/premature signs of aging
    • after one reaches puberty
    • hair loss
    • greying of hair
    • skin ulcers
    • osteoporosis (bone thinning)
    • 'bird-like' face
  • Multiple rare cancers
  • Average life span: 40-50 years
    • heart attacks
    • diabetes
    • cancer
    • osteoporosis
  • Treatments & therapies are available for
    • Skin ulcers
    • Ocular cataracts
    • Malignancies
    • Controlling Type II diabetes mellitus
    • Cholesterol-lowering drugs
  • Cancers/other diseases can be prevented if Werner's syndrome is diagnosed early
  • No cure for Werner's syndrome
Huntington's Disease
  • As gene passes from generation to generation, number of repeats increases and symptoms become more evident at younger and younger ages
  • If one of your parents has HD, you have a 50% chance of inheriting it
  • Genetic disease, therefore cannot be developed over time if you did not inherit it from your parents
  • Mutation on HTT gene on Chromosome 4 causes HD
  • HTT gene holds instructions to make the protein Huntington to distribute to parts of brain and tissues in body
  • CAG trinucleotide repeats more than needed throughout DNA
  • Normally repeated 10 to 35 times, but person with HD repeats 36 to 120 times
  • These repeated segments cause protein synthesis (Huntington proteins) - contain large sections of amino acid & glutamine
  • Reduction of brain cells in basal ganglia
  • Mood swings
  • Depression
  • Irritability
  • Trouble driving, learning new things, remember facts, & making decisions
  • Lack of concentration
  • Difficulty feeding themselves & swallowing
  • Involuntary/purposeless movements of face, legs, arms, A.K.A. chorea
  • Personality changes
  • Slurred speach
  • Memory loss
  • No cure
  • Desipramine used to slow down symptoms of depression
  • Tetrabenazine used to slow down symptoms of chorea
  • Transplantation of dopamine-containing cells has been attempted, needs further research
  • Stem cell research