1. Down Syndrome Analyze the karyotype:
There are 3 number 21 chromosomes. This is called Trisomy 21
(tri:3, somy:body)
Down Syndrome

2. Chapter 13 - Meiosis and Sexual Life Cycles
AIM: What happens when meiosis goes wrong?

3. What about if non-disjunction occurs in the sex chromosomes?
Chapter 13 - Meiosis and Sexual Life Cycles
AIM: What happens when meiosis goes wrong?
What about if non-disjunction occurs in the sex chromosomes?

4. Chapter 13 - Meiosis and Sexual Life Cycles
AIM: What happens when meiosis goes wrong?
Klinefelters XXY can be multiples of X with one Y
Most common sex chromosome disorder
And second most common extra chromosome condition next to Down Syndrome
Small testicles and reduced fertility
The syndrome was named after Dr. Harry Klinefelter, an endocrinologist at Massachusetts General Hospital in Boston, Massachusetts, who first described it in 1942.
Klinefelter’s Syndrome (XXY)
- Sterile male typically
- Female characteristics

5. Chapter 13 - Meiosis and Sexual Life Cycles
AIM: What happens when meiosis goes wrong?
XXXXY
Klinefelter’s syndrome: can be any multiple of X with a single Y.

6. Chapter 13 - Meiosis and Sexual Life Cycles
AIM: What happens when meiosis goes wrong?
Life expectancy reduced by 10 years in turners
Turner Syndrome
- Shorter stature (height)
- Enlarged hands and feet
- Underdeveloped ovaries (infertile)
- Other problems (high blood pressure, heart problems, etc…)

7. Chapter 13 - Meiosis and Sexual Life Cycles
AIM: What happens when meiosis goes wrong?

8. Chapter 13 - Meiosis and Sexual Life Cycles
AIM: What happens when meiosis goes wrong?
Triple X syndrome
No real symptoms since female only have one active X per cell (other X chromosomes are condensed and shut down – barr bodies)
(normal for the most part)

9. Chapter 13 - Meiosis and Sexual Life Cycles
AIM: What happens when meiosis goes wrong?
What is the total number of chromosomes you would expect to find in a woman with Turner syndrome?
45, missing one X

10. 1. Deletions 2. Duplications 3. Inversions 4. Translocations
Chapter 13 - Meiosis and Sexual Life Cycles
AIM: What happens when meiosis goes wrong?
Other mishaps can occur during meiosis resulting in chromosomal abnormalities that may cause disease. These abnormalities include…
1. Deletions
2. Duplications
3. Inversions
4. Translocations

11. Chapter 13 - Meiosis and Sexual Life Cycles
AIM: What are some other ways chromosomes can be altered?
There is a “mistake” made during meiosis resulting in the loss of a chromosome segment.
Deletion - occurs in meiosis typically
2/3 of Duchenne’s muscular dystrophy
-starts age 2 to 6
-general muscle weakness and failure
-survival beyond 20 years is rare
-dystrophin gene (largest in genome-2.4megabases, 16 hours to transcribe, 14kb mature mRNA, 3500 amino acids) - X-linked recessive - dystophin protein involved in connecting cytoskeleton to ECM in muscle cells
Cri du chat 1 in 20,000 to 50,000 - deletion in chromosome 5
- trouble sucking and swallowing, low birth weight, cognitive delays, motor, speech problems
- can reproduce
-normal life span
Williams syndrome - deletion of 26 genes in chromosome 7
-elf’in like facial appearance, unusually cheerful, unpredictable negative outbursts, mental retardation
-shortened life span usually due to narrowed arteries (cardiovascular including heart problems)

12. Chapter 13 - Meiosis and Sexual Life Cycles
AIM: What are some other ways chromosomes can be altered?
Diseases caused by deletions include:
1. Cri du chat
“cry of the cat”
- Cat-like cry
- Low birth weight, cognitive (information processing) delays, motor (movement) and speech problems
Deletion - occurs in meiosis typically
2/3 of Duchenne’s muscular dystrophy
-starts age 2 to 6
-general muscle weakness and failure
-survival beyond 20 years is rare
-dystrophin gene (largest in genome-2.4megabases, 16 hours to transcribe, 14kb mature mRNA, 3500 amino acids) - X-linked recessive - dystophin protein involved in connecting cytoskeleton to ECM in muscle cells
Cri du chat 1 in 20,000 to 50,000 - deletion in chromosome 5
- trouble sucking and swallowing, low birth weight, cognitive delays, motor, speech problems
- can reproduce
-normal life span
Williams syndrome - deletion of 26 genes in chromosome 7
-elf’in like facial appearance, unusually cheerful, unpredictable negative outbursts, mental retardation
-shortened life span usually due to narrowed arteries (cardiovascular including heart problems)
- Chromosome 5 deletion
- Life span is normal

13. Chapter 13 - Meiosis and Sexual Life Cycles
AIM: What are some other ways chromosomes can be altered?
Diseases caused by deletions include:
2. Williams syndrome
- Deletion of 26 genes in chromosome 7
- Elf like facial appearance
Deletion - occurs in meiosis typically
2/3 of Duchenne’s muscular dystrophy
-starts age 2 to 6
-general muscle weakness and failure
-survival beyond 20 years is rare
-dystrophin gene (largest in genome-2.4megabases, 16 hours to transcribe, 14kb mature mRNA, 3500 amino acids) - X-linked recessive - dystophin protein involved in connecting cytoskeleton to ECM in muscle cells
Cri du chat 1 in 20,000 to 50,000 - deletion in chromosome 5
- trouble sucking and swallowing, low birth weight, cognitive delays, motor, speech problems
- can reproduce
-normal life span
Williams syndrome - deletion of 26 genes in chromosome 7
-elf’in like facial appearance, unusually cheerful, unpredictable negative outbursts, mental retardation
-shortened life span usually due to narrowed arteries (cardiovascular including heart problems)
- Unusually cheerful
- Unpredictable negative outbursts
- Mental retardation
- Shortened life span due to narrowed arteries

14. Chapter 13 - Meiosis and Sexual Life Cycles
AIM: What are some other ways chromosomes can be altered?
Diseases caused by deletions include:
3. Duchenne’s muscular dystrophy
i. Dystrophin gene
- Largest gene in genome
Deletion - occurs in meiosis typically
2/3 of Duchenne’s muscular dystrophy
-starts age 2 to 6
-general muscle weakness and failure
-survival beyond 20 years is rare
-dystrophin gene (largest in genome-2.4megabases, 16 hours to transcribe, 14kb mature mRNA, 3500 amino acids) - X-linked recessive - dystophin protein involved in connecting cytoskeleton to ECM in muscle cells
Cri du chat 1 in 20,000 to 50,000 - deletion in chromosome 5
- trouble sucking and swallowing, low birth weight, cognitive delays, motor, speech problems
- can reproduce
-normal life span
Williams syndrome - deletion of 26 genes in chromosome 7
-elf’in like facial appearance, unusually cheerful, unpredictable negative outbursts, mental retardation
-shortened life span usually due to narrowed arteries (cardiovascular including heart problems)
- 2.4 million base pairs!!!!!!!!!
- Takes 16 hours to transcribe (to make a mRNA)!!!!!!!
- Protein is 3500 amino acids!
- X linked gene (means it is on the X-chromosome)
- Function: connects muscle cell cytoskeleton to ECM (anchors cell to ECM)

15. Chapter 13 - Meiosis and Sexual Life Cycles
AIM: What are some other ways chromosomes can be altered?
Diseases caused by deletions include:
3. Duchenne’s muscular dystrophy
ii. Symptoms begin at 2 to 6 years old
iii. Develop muscle weakness and eventually failure
Deletion - occurs in meiosis typically
2/3 of Duchenne’s muscular dystrophy
-starts age 2 to 6
-general muscle weakness and failure
-survival beyond 20 years is rare
-dystrophin gene (largest in genome-2.4megabases, 16 hours to transcribe, 14kb mature mRNA, 3500 amino acids) - X-linked recessive - dystophin protein involved in connecting cytoskeleton to ECM in muscle cells
Cri du chat 1 in 20,000 to 50,000 - deletion in chromosome 5
- trouble sucking and swallowing, low birth weight, cognitive delays, motor, speech problems
- can reproduce
-normal life span
Williams syndrome - deletion of 26 genes in chromosome 7
-elf’in like facial appearance, unusually cheerful, unpredictable negative outbursts, mental retardation
-shortened life span usually due to narrowed arteries (cardiovascular including heart problems)
iv. Wheelchair by age 12
v. Survival beyond 20 years old is rare
vi. Affects 1 in 3500 MALES