Congenital And Genetic Disorders, Pathophysiology

Front 1

1. Differentiate between autosome and chromosome.

Back 1

Of the 23 pairs possessed by humans, 22 pairs are autosomes (non-sex) and they are numbered when arranged by size and shape in a term called karyotype.

The 23rd pair consists of a pair of sex chromosomes, males have XY and females have XX chromosomes.

Front 2

2. Chromosomes are made up of many genes, which tend to be matched for a function (allele) at a specific location on the paired chromosomes. True/False

Back 2

True.

Front 3

3. What exactly is a gene?

Back 3

A gene is a specific file of DNA, on the chromosome that has the necessary data or information regarding protein synthesis in the cell.

All cells in a person's body has the same chromosomes and genes for the same traits. This is called a genotype. Not all genes within the cell are active. Those that are are referred to as gene expression.

Front 4

4. What are genes composed of?

Back 4

They have DNA strands, which can determine the function of all cells in the body.

Front 5

5. What is the function of RNA?

Back 5

Ribonucleic acid is responsible for the communication link with DNA during the synthesis of proteins. It also assists in control of cell activity.

Front 6

6. What is a mutation?

Back 6

Within cells, the same genetic information is physiologically carried forward. Errors can occur, either within the meiotic or mitotic process, though these are not that common.

A mutation is an alteration of genetic material. It can be spontaneous or can result from exposure to harmful substances such as radiation, chemicals, drugs or other substances.

Front 7

7. What is a single gene disorder.

Back 7

These are changes in 1 gene within the reproductive cells (ova or sperm). This gene will be transmitted to subsequent generations.

Front 8

8. Are all mutations transmitted to offspring?

Back 8

No.Mutations in body cells other than reproductive cells may cause some dysfunction but tend not to be transmitted to offspring.

\In some cases,, the expression of an altered gene produces clinical signs that can vary in severity. Genetic disorders may not always be present at birth, but can surface months or years later. Huntingdon disease is an example of such a process.

Front 9

9. Regarding single gene disorders, list 4 autosomal dominant and 4 autosomal recessive disorders.

Back 9

Autosomal dominant:

1. Adult polycystic kidney disease

2. Huntingdon's disease

3. Familial hypercholesterolemia

4. Marfan syndrome.

(AHFM)

Autosomal recessive:

1. Cystic fibrosis

2. Phenylketonuria

3. Sickle cell anemia

4. Tay-Sachs disease.

(CPST)

Front 10

10. List 1 X linked dominant disorder and 3 X linked recessive disorders.

Back 10

X linked dominant:

1. Fragile X syndrome

X linked recessive disorders:

1. Color blindness

2. Duchenne muscular dystrophy

3. Hemophilia A

Front 11

11. List 6 multifactorial disorders.

Back 11

1. Anencephaly

2. Cleft lip

3.Clubfoot

4.Congenital heart disease

5. Myelomeningocele

6. Schizophrenia

Front 12

12. List 4 chromosomal disorders.

Back 12

1. Down syndrome

2. Monosomy X (Turner syndrome)

3. Polysomy X (Klinefeletr syndrome)

4. Trisomy 18 (Edward's syndrome)

Front 13

13. What do chromosomal anomalies usually result from?

Back 13

They generally result from an error during meiosis, when the DNA fragments are displaced or lost, altering the genetic code information. This is typical of Down's syndrome.

Front 14

14. What might be the causes of other congenital or developmental disorders?

Back 14

These can result from premature birth, a difficult labor and deliver6y. Occasionally exposure to a damaging agent during fetal development, may result in a congenital defect.

Most of these disorders do not have a genetic component.

Front 15

15. What is a teratogenic agent?

Back 15

These are agents that cause damage during embryonic or fetal development. The drug. Thalidomide is an example of such an agent.

Front 16

16. Briefly describe Thalidomide.

Back 16

Thalidomide sold under the brand names Immunoprin, among others, is an immunomodulatory drug and the prototype of the thalidomide class of drugs. Today, thalidomide is used mainly as a treatment of certain cancers (multiple myeloma) and of a complication of leprosy.Thalidomide was first marketed in 1957 in West Germany under the trade-name Contergan. The German drug company Chemie Grünenthal developed and sold the drug. Primarily prescribed as a sedative or hypnotic, thalidomide also claimed to cure "anxiety, insomnia, gastritis, and tension".[3] Afterwards, it was used against nausea and to alleviate morning sickness in pregnant women.
It was learned that Thalidomide resulted in a condition called Phocomelia. Infants were born with deformed or missing limbs.

Front 17

17. In recessive disorders, both parents must pass on the defective gene. True/False

Back 17

True. The result will be an affected homozygous child.

Front 18

18. What does it mean if a child is homozygous?

Back 18

In a heterozygous situation, one normal gene and one diseased gene are present. In this case, the child is considered a carrier and does not show any signs of the disease.

Front 19

19. What is the probability of inheritance if in each pregnancy, each parent is heterozygous for the recessive disease trait?

Back 19

Probability:

25% that the child is born with an unaffected genotype.

50% that the child is born with a carrier genotype.

25% that the child will be born with the affected or diseased genotype.

Front 20

20. What is the probability if only one parent carries the recessive gene for the disease?

Back 20

There will be a 50% probability of the child being a carrier and a 50% probability of having the unaffected genotype.

Front 21

21. Many of these recessive gene disorders involve what type of defect?

Back 21

Many involve some enzyme defect which results in the accumulation of toxic metabolites inside cells or in the tissues and bklood. Cell function is often compromised.

Front 22

22. regarding the above question, give an example of such a condition.

Back 22

PKU or Phenylketonuria is defined as a deficiency of the enzyme phenylalanine hydroxylase. This enzyme is necessary in order to convert phenylalanine into tyrosine. The failure to do this will result in toxic levels of phenylalanine, which can cause CNS damage if phenylalanine is present in the diet.

Front 23

23. Do all genes fully fit either the recessive or the dominant pattern?

Back 23

No. An example would be sickle cell disease, which is transmitted as a recessive gene, but may also be referred to as incompletely dominant, because heterozygotes may display some clinical signs (sickle cell trait). Homozygotes will show the full impact of the disease.

Front 24

24. Define autosomal dominant disorders.

Back 24

In this condition, the presence of the defect is in only one of the alleles and produces clinical expression of the disease.

An affected parent has a 50% probablity of passing the disease onto each child regardless of the gender of the child.

Front 25

25. Fragile X syndrome is the most common cause of mental retardation and learning disorders in North America. True/False

Back 25

True. The mutation responsible for this syndrome is inherited as a dominant allele carried on the X chromosome, thus males and females can both be affected. The mutation causes the affected X chromosome to appear constricted or broken.

Front 26

26. Alleles for sex linked recessive disorders are usually carried by which chromosome.

Back 26

The X chromosome. Thr Y chromosome does not carry the same genes as does the X.

The genes for X linked disorders are recessive but are manifested in herterozygous males who lack the matching normal gene on the Y chromosome.

Front 27

27. Give 2 examples of X linked recessive disorders.

Back 27

1. Hemophilia A

2. Duchenne muscular dytrophy

Carrier females have a 50% chance of producing an affected male child and an equal chance of producing a carrier female child in each pregnancy.

Front 28

28. In X linked recessive disorders, how will a male transmit the defect?

Back 28

He will transmit the defect to all his daughters, who become carriers, whereas his sons will neither be affected, nor will they be carriers.

The male can pass only the normal Y chromosome to his sons.

Front 29

29. In X linked recessive disorders, females are carriers, when they are heterozygous. They do not demonstrate clinical signs. True/ False

Back 29

True.

Front 30

30. What is trisomy, and in which condition is it seen?

Back 30

Down syndrome is such an example, in which there are three chromosomes rather than the usual two in the 21 position. This is trisomy 21.

Front 31

31. An individual with Down syndrome has how many chromosomes?

Back 31

47 chromosomes.

Front 32

32. In the Down syndrome condition, what is translocation?

Back 32

This exists in a less common form of Down syndrome. A part of chromosome 21 is attached to another chromosome.

Front 33

33. What is Monosomy X?

Back 33

Also known as Turner's syndrome, this develops when only one sex chromosome, the X chromosome, is present.

This individual possesses 45 chromosomes.

There are noted physical abnormalities and a lack of ovaries.

Front 34

34. What is Polysomy X?

Back 34

Also known as Kleinfelter's syndrome, an extra chromosome is present as in XXY, resulting in a total of 47 chromosomes in each cell.

Not all male swill show signs, however, generally the testes are small and sperm are not produced.

Front 35

35. Define Proteomics.

Back 35

Proteomics is the science of identifying the proteins associated with the expression of a particular gene for the purpose of designing drugs in order to replace missing proteins or inhibit the effects of damaging proteins.

Front 36

36. What is Alpha-feto protein?

Back 36

AFP is the most abundant plasma protein found in the human fetus. Plasma levels decrease rapidly after birth but begin decreasing prenatally starting at the end of the first trimester. Normal adult levels are usually achieved by the age of 8 to 12 months. The function of AFP in adult humans is unknown; however, in rodents it binds estradiol to prevent the transport of this hormone across the placenta to the fetus. The main function of this is to prevent the virilization of female fetuses. As human AFP does not bind estrogen, its function in humans is less clear.[7]