Tay-Sachs Disease

The disease is a deterioration of mental and physical abilities. It is caused by a genetic defect in a gene inherited from each parent.



-severe genetic condition
Six months old=diagnosed. There are seizures and behavior changes. As progression gets worse (6-10 months), they lose motor skills and sight. Usually death by age 5
There is no cure or treatment for the disease. There are 16 cases in America every year.

Huntington's Disease-Autosomal Dominant

To the bottom, the brain of a person with Huntington’s disease (top) vs. a normal brain (bottom)



The nerves are slowly destroyed.
-Huntington’s disease (HD) occurs when there is a large amount of CAG codon repeats within the Huntington gene.
-The disease is located on chromosome 4 at 4p16.3
-It begins at middle age (30’s or 40’s) and can cause premature death.


Symptoms (just a few)
-Difficulty moving
-Can’t speak very well
-loss of physical coordination
It is most common with European Ancestry (5 in 100,000 people)
-There is no cure. The progress can’t even be slowed. There is research for a cure being constructed.
Treatment can reduce some of the affects.

Lifestyle-depending on the number of codon repeats, influences the lifespan of a person
In order to stay healthy for as long as possible
-Speech therapy
-Maintain physical activity
-Keep up proper nutrition
-adequate fluids

Cancer Types

Cancer with correct type
Carcinomas-Breast, Colon, Eye, Kidney, Lung, Pancreatic, Prostate


Sarcomas-Muscle and bone
This is a picture of Synovial Sarcoma which occurs most commonly in young adults. The causes are still unknown. Most cases develop in the leg region and the next most common is in the arm. It can be controlled through radiation therapy.


Melanomas-Skin


Lymphomas and Leukemia’s-Red or white blood cells.

Cancer

The following questions will give you a better understanding of Cancer…
1. True or False, Cancer is not one disease?
True. It is a group of related diseases. It is a genetic disease. All cancers are due to mutations in the gene. Cancer= abnormal division of cells. It is loss of normal growth control.
2. True or False, Benign tumors are never a threat to life?
False. They are rarely a threat to life but they can be if their growth interferes with function on vital organs in which they can be located.
3. What is the primary difference between benign and malignant tumors?
Benign (not cancer) grow locally and cannot spread. Malignant (cancer) cells invade neighboring tissues and enter blood vessels. Every malignant comes from benign but benign don’t always turn into malignant.


4. What is meant by the term metastasis?
Metastasis carries it through the blood stream and to other parts of the body.
5. True or False, Cancers may be inherited?
False. Some gene alterations are inherited however having the gene does not mean the person will receive cancer.
6. Identify three types of cells with respect to their pattern of division.
• Cells continually dividing.
• Cells that have stopped dividing but can divide when repairs are required.
• Cells that have stopped dividing and will not divide again.

There are two types of checkpoint genes.
• Go proteins-Oncogenes (there is too much acceleration and they can’t stop)
• Stop proteins-Tumor suppressor (genes taken break away)

Causes of cancer
50-80% of cancer is cause by lifestyle choices
1. Ionizing Radiation-high energy radiation that comes from the sun.
2. Non-ionizing radiation –ultra violet light (UV rays). Low energy SPF 30 is really the highest in sunscreen you need to go. Once past that it doesn’t really do anything else.
3. Chemical compounds-Tobacco use. There is a twenty year between smoking and cancer. (twenty year what?)
4. Viruses-HPV(cervical cancer) HIV(Aids) HHV8(Kaposi’s Sarcoma)
5. Bacteria-Helicobacter pylori-causes stomach ulcers. Leads to cancer
6. Heredity- Example is breast cancer patients.
7. Aging-the older you get, the more likely you will be to get cancer
8. Ethnic Population-colon cancer in the U.S, stomach cancer in Japan from seafood and alcohol, skin cancer in Australia.

Modes of Inheritance

There are various modes of inheritance for different mutations/diseases including:
•Autosomal Dominant-females and males are equally likely to have a trait. The trait does not skip generations. Affected children have one affected parent. There is a male to male transmission (meaning that if a dad has it, it is automatically passed on to the suns)
•Autosomal Recessive- males and females are equally likely to inherit the trait. It is known to skip generations. Children can be born to unaffected parents (who are carriers)
•X-linked Recessive-more often occurs in males than females. Generally known to skip one or more generations. Affected males are usually born to unaffected females (carriers)
Females who are affected must have a father that is affected or it has to be autosomal
There is no male-to-male transmission
•X-linked Dominant-twice as many females as males are affected. The mutation doesn’t skip generations. Generally females will pass the trait to half of their children. Sons and daughters are equally affected. All daughters of affected males are affected. There is no male-to-male transmission. Dad gives to 100% female and 0% to males.
•Y-linked-Only males are affected. All sons of affected males will be affected as well. The trait doesn’t skip generations.

What is this inheritance?


Autosomal Dominant!
It does not skip generations. Females and males are equally likely to have the trait. Affected children have one affected parent.

Inheritance

Inheritance
Gene-Simply part of your appearance. It is one unit that was inherited at conception. (Ex. The color of your hair)
Allele-an alternate form of a gene. (Ex. Red vs. non red)
Dominant vs. Recessive-Some genes are dominant and some are recessive. The dominant always cover up the recessive.
Homozygous vs. Heterozygous- Homozygous is where there are two of the same alleles. Heterozygous is two different alleles.
Genotype vs. Phenotype-Genotype is what is inside the nucleus. You can’t see what is on the inside but the phenotype is the physical appearance of a person.

Questions to think about…
When two black mice crossed together, produced black and white offspring what is the genotype of the parents? Hint: black is dominant

Answer: Heterozygous. Since there was a white mouse that means both parents had to be carriers of the white gene because white is recessive.



If bill is albino what is his genotype?

Answer: Homozygous Albino. The gene for Albino is recessive so
he had to receive that gene from both parents.

If Rex (doesn’t suffer from migraines) and Linda (who has them regularly) were to get married and have children, what is the chance of passing migraines on?

Answer: There is a 50% chance.
To determine potential offspring, it is best to do a punnett square crossing the different options for the alleles.
Example problem: Foxes, Gold coat is governed by a recessive allele g and red color by a dominant allele G. Determine the genotypic ratios from the following mating.



By looking at the punnett square, we can conclude that the genotype would be 25% homozygous dominate and 50% heterozygous and 25% homozygous recessive. 75% of the foxes would come out Red dominant and 25% would come out gold recessive.

X Linked- only appears on the X chromosome
Y Linked-only appears on the Y chromosome. Never will be in females. It is hemizygous and passed from father to all sons.
Sex Limited- the trait is on the autosomes and is only found in one gender.
Sex influenced-on the autosomes. It occurs in both genders but is dominant in one over the other

Chromosome Disorders

1.The term that means an extra or missing chromosome is Aneuploidy.
2.An example of an aneuploidy is Down syndrome.
3.A section of chromosomes gets turned around, reversing the order of the genes is Inversion.
4.Term that means identical twins is Monozygotic.

Aneuploidy
•Caused by nondisjunction during meiosis.
•Nullisomy (2n-2): Missing both copies of one chromosome
•Monosomy (2n-1): Missing one chromosome

Polyploidy-having more than two sets of chromosomes.
•Causes
-errors in meiosis: results in diploid gametes
-events at fertilization: dispermy- two sperm cells penetrate and fertilize the egg.

Human Chromosome Disorders
Monosomy
Missing one chromosome from a pair
•Rare in live births
•turner syndrome (45, x): xo female. The female is missing an x chromosome
•causes-nondisjunction in meiosis or mitosis




Notice in the picture that the last chromosome only contains one allele when it should have two.


Trisomy (more common than monosomy)
Trisomy is an abnormality in which there are three copies, instead of two, of chromosomes. It is a type of aneuplodiy
•13 (Patau Syndrome)
-cleft palate, eye defects…
•18 (Edward Syndrome)
-small birth weight, slow growth
•21 (Down Syndrome)
-translocation of chromosome 21 (usually)
• Deletion of chromosome 15
-Cri-du-chat & Pradar-willi syndrome
Translocation (one piece changes play but the other doesn’t. It is deletion)