1. Human Genetic disorders
A look into a few different types

2. About Human Genetic Disorders
Any illness caused by abnormalities in genes or chromosomes
Most are rare
May or may not be heritable

3. Broad Types of Genetic Disorders
Single Gene Disorder – result of a single mutated gene.
X-Linked Dominant – mutations on genes of the X chromosme
Men and women are equally likely to get it
Rett Syndorme (degenerative brain disorder)
Fragile X
X-Linked Recessive – again, mutations on the genes of the X chromosome
Males way more likely to get these than women
Duchenne Muscular Dystrophy
Hemophilia
Y-Linked – mutations in genes on the Y chromosome
ALL males will have these disorders
Rare since the Y chromosome is small

4. Autosomal dominant – only one mutated copy of the gene is needed
Marfan Syndrome
Huntington’s Disease
Retinoblastoma
Autosomal recessive – two mutated copies of the gene are needed to be affected
Sickle cell anemia
Cystic fibrosis
Tay-Sachs

5. Insight to a few human genetic disorders
Let’s take a look
Insight to a few human genetic disorders

6. Achondroplasia
Mutation in a gene on chromosome #4 that makes a protein that is involved in converting cartilage to bone
A form of dwarfism
In MOST cases is it NOT inherited but in rare cases that it is, it is autosomal dominant

7. Achondroplasia Occurs in 1 in ever 15,000-40,000 live births
Often these children are born to normal sized parents
Not fatal
No treatment but monitoring of height, weight, and head circumference.

8. Achondroplasia Symptoms: Abnormal bone growth
Short stature with disproportionately short arms and legs
Short fingers
Large head
Prominent forehead
Bowed legs
Weak muscles
Causes delays in walking and other motor skills

10. Duchenne Muscular Dystrophy
A disease characterized by progressive loss of muscle function and weakness beginning in the lower limbs.
A sex-linked recessive disorder – body does not make the muscle protein dystrophin
Occurs mostly in boys
Affects 1 in 3500 births

11. Duchenne Muscular Dystrophy
Symptoms (appear between ages 1-6):
Delays in motor skill milestones like sitting or walking
Progressive muscle weakness in the legs and pelvic muscles
Loss of muscle mass
Abnormal bone development
By age 10, leg braces are required for walking
By age 12, confinement to a wheelchair
In the early teens, complications due to an enlarged heart appear and few individuals live past their 30’s/

13. Turner’s Syndrome
A disease characterized by females having only ONE X-Chromosome instead of two
The second X-Chromosome may be entirely missing or severely mutated
Causes delays in the development of females

14. Turner Syndrome
Occurs in 1 in ever 2500 births but is more common in non-surviving pregnancies
This is NOT an inherited disorder, it is due to nondisjunction during meiosis – chromosomes do not separate properly

15. Turner Syndrome Symptoms Extra skin on neck Short stature
Swelling of hands and feet
Skeletal abnormalities
Heart defects
Developmental delays
Most females with this disease are infertile and do not go through puberty unless they are given hormones

17. Cri-du-Chat
Part of chromosome #5 is missing. The more genes missing, the more severe the symptoms
Characterized by infants with this syndrome having a high pitched cry that sounds like that of a cat
Occurs in 1 in every 20,000 – 50,000 births
NOT in inherited disorder

18. Cri-du-Chat Delayed development Small head size Low birth weight
Weak muscle tone in infants
Low set ears
Widely set eyes
Small jaw
Round face
Possibility of heart defects

20. Huntington’s Disease
An autosomal dominant disorder caused by a CAG repeat on chromosome #4. Normally this gene should have repeats but people with HD have between The more repeats, the more likely your symptoms will start earlier and be more severe.
IS an inherited disorder. If one of your parents has it you have a 50% chance of getting it.

21. Huntington’s Disease
Most common form begins in adults in their mid ’s.
Symptoms
Behavior changes
Hallucinations
Moodiness
Paranoia
Psychosis

22. Huntington’s Disease Symptoms Dementia Abnormal or Unusual Movements
Disorientation or confusion
Loss of memory
Loss of judgement
Personality changes
Abnormal or Unusual Movements
Jerky, sudden movements of the limbs
Slow, uncontrolled movements
Unsteady walk

23. Huntington’s Disease
Can use a neurological exam, MRI, or genetic exam to detect symptoms
Eventually for a person with HD, 24 care will be needed and death occurs years after the symptoms first present themselves
There is no treatment, it is 100% fatal however many different medications can be prescribed to treat the symptoms
Antipsychotics
Dopamine blockers

25. HD BRAIN
NORMAL BRAIN