Genetic Influence in Disease

Question 1

GENETIC DISORDERS

Answer 1

A disease caused by abnormalities in an individual’s genetic material

Can either be spontaneous or inherited

Question 2

MITOCHONDRIAL DISORDERS

Answer 2

Disorder caused by the mutation or alteration of the minute amounts of DNA found in the mitochondria. Very uncommon

Question 3

MULTIFACTORIAL GENETIC DISORDERS

Answer 3

Disorders caused by environmental triggers and variations/mutations of genes, plus sometimes inherited tendencies

Examples include cancers, common disease (HTN, DMII, CAD), and teratogenic disorders

Question 4

TERATOGENIC DISORDERS

Answer 4

A teratogen is any influence (drugs, radiation, viruses) that can cause congenital defects

Abnormalities that are either detectable at birth and/or can be attributed to fetal development “glitches”

Question 5

CHROMOSOMAL DISORDERS

Answer 5

Genetic disorders that result from alterations to the numbers or structure of a chromosome. This alters the local genes - the genes functionality is disrupted and won’t code proteins properly

Question 6

ANEUPLOIDY

Answer 6

Alteration to the NUMBERS of chromosomes. A generic term for “more than usual numbers of chromosomes” would be polysomy.

Question 7

DOWN’S SYNDROME

Answer 7

A disorder of abnormal numbers of chromosomes that are generally associated with pregnancies of women > 35 years old.

Occurs very early in cellular division, through a glitch in chromosomal distribution.

The fetus ends up with 47 chromosomes, the extra chromosome being on the 21st chromosome set. Another name for Down’s is Trisomy 21

Includes: mental retardation, low-set ears, epicanthic fold to the eyes, short limbs, and large tongue

Question 8

PHILADELPHIA CHROMOSOME

Answer 8

This is an example of alterations to the STRUCTURE of chromosomes

Caused by alterations in chromosomal structure - such as deletion, duplication, or rearrangement of gene sites (translocation)

Question 9

SINGLE-GENE DISORDERS

Answer 9

Disorders that are usually due to an inherited mutated gene.

Mutated genes produce poor protein products that can no longer carry out their normal functions

Include: autosomal recessive, autosomal dominant, and sex-linked

Question 10

AUTOSOMAL RECESSIVE DISORDER

Answer 10

Occurs when a mutated recessive gene partners with an allele that is also recessive and mutated

Notated with two lowercase letters ( aa )

Question 11

SICKLE CELL ANEMIA

Answer 11

Abnormal recessive alleles will code for abnormally-shaped hemoglobin (sickle-shaped) which will makes red blood cells sickle-shaped. ( ss )

More easily damaged red blood cells as they go through the blood stream, leading to abnormally low numbers of RBCs, leading to anemia

Question 12

SICKLE CELL ANEMIA (S&S/Patho)

Answer 12

S&S: Shortness of breath, weakness, and fatigue due to decreased oxygen being carried to tissues in the body
Patho: anemia – less numbers of red blood cells to carry the hemoglobin which in turn carries the oxygen
Deformed hemoglobin can’t carry the usual numbers of oxygen molecules

S&S: Ischemic pain, especially in the points
Patho: deformed red blood cells clog up the capillaries that usually carry oxygen rich blood to tissues
Distal tissues are starved for oxygen

ss: sickle cell anemia
Ss: “having the trait”, very rarely exhibit S&S, but are carriers and can pass the trait (heterozygous)
SS: does not have disease and is not a carrier (homozygous)

Question 13

AUTSOSOMAL DOMINANT DISORDERS

Answer 13

Occurs when a person inherits a mutated gene that is dominant. The disease characteristic is dominant, the normal characteristic is recessive ( Aa )

Question 14

POLYCYSTIC KIDNEY DISEASE (PKD)

Answer 14

During fertilization, a kidney tissue gene is inherited that has a mutation and will code for abnormal kidneys. Regardless of what gene is paired with this gene, it will override that gene as it is the dominant of the two.

Kidney tissue commonly develops cysts, which reduces normal kidney functions and leads to kidney failure as the patient goes through life

Question 15

POLYCYSTIC KIDNEY DISEASE (S&S/Patho)

Answer 15

S&S: hematuria (blood in urine), proteinuria (protein in urine), frequent kidney infections
Pain at costovertebral angles and abdomen
Kidney stones

PP / Pp: PKD
pp: normal kidneys

Question 16

SEX-LINKED DISORDERS

Answer 16

Generally known as X-linked disorders.

Women are XX and each allele is partnered to the same locus on the other allele. So if one X allele is diseased it is protected by a normal dominant allele on the other X
Men are XY and therefore do not have comparable partner alleles between the X chromosome and Y chromosome. Therefore, almost all sex-linked disorders occur in male offspring

Can be X-linked dominant, X-linked recessive, and Y-linked

Question 17

HEMOPHILIA

Answer 17

Caused by mutations on the X chromosome.

Gene for coagulation factors that facilitate normal clotting factors (Factor XIII and Factor IX) are mutated, resulting in an altered ability to clot properly.

Genotypes are different than normal alleles, since they are sex linked:
Xh XH, XH XH, or XH Y

Question 18

RECOMBINANT DNA

Answer 18

A form of genetic engineering, which results in “new” DNA by combining two ore more different sources of DNA.

Applications include:
Human growth hormone for children lacking it
Exogenous insulin for diabetics
Factor VIII for hemophiliacs
tPA and tenecteplase - “clot-busters” for patients having myocardial infarctions.