HD EX 1 DISEASES PRESENTED AT BIRTH (4)

Question 1

3 types of diseases presented at birth:

Answer 1

1. Chromosomal Aberrations
2. Genetic Defects
3. Congenital Defects

Question 2

CHROMOSOMAL ABERRATIONS:

Each cell has how many chromosomes (except gamate cells)?

Answer 2

23 pairs = 46 chromosomes

Question 3

How many chromosomes do gamate cells have?

Answer 3

23 chromosomes

Question 4

Chromosome slide shows:

Answer 4

normal male karyotype.

Question 5

What are the 22 pairs called? What is the 23rd pair called?

Answer 5

1-22 is autosomes. 23rd is the sex-linked chromosome.

Question 6

What is trisomy?

Answer 6

Extra chromosome.

Question 7

Down Syndrome is called…

Answer 7

Trisomy-21. There is an extra 21st chromosome.

Question 8

What are characteristics of down syndrome?

Answer 8

Slanted eyes with round face.
Short, stocky stature.
Learning deficiency yet extremely good disposition.
Sub-par immune system so tend to be sickly.
Usually develop Alzheimer’s if survive to age 60.

Question 9

Klinefelter’s Syndrome is called…

Answer 9

Trisomy-23. There is an extra 23rd sex chromosome = XXY.

Question 10

What are characteristics of Klinefelter’s Syndrome?

Answer 10

Male genitalia at birth.
Secondary female traits during puberty like gynecomastia (breast tissue) and pelvic girdle widens.
Some learning impairment.
Usually are sterile.

Question 11

Turner’s Syndrome is called…

Answer 11

Monosomy-23. There is only one sex chromosome = Xo. This individual only has 45 total chromosomes.

Question 12

What are characteristics of Turner’s syndrome?

Answer 12

Female genitalia at birth.
Minimal changes at puberty like lack of breast development, pelvis does not widen, and sterile.
Very bright!
Turner’s responds to hormone therapy if diagnosed early enough and can become fertile again and have kids.

Question 13

GENETIC DEFECTS:

What is autosomal recessive genetic disease?

Answer 13

Autosomal recessive is one of several ways that a trait, disorder, or disease can be passed down through families. It can happen on any of the 1-22 chromosomes (not the 23rd sex chromosome).

Question 14

Genes line up in pairs in the…

Answer 14

chromosomes.

Question 15

Each gene of the pair is referred to as an…

Answer 15

allele.

Question 16

Alleles can be…

Answer 16

dominant or recessive.

Question 17

Dominant means…

Answer 17

always manifests no matter what other allele it is paired with.

Question 18

Recessive means…

Answer 18

has to be paired with another recessive allele to manifest.

Question 19

What are the 3 possible gene pairing combinations?

Answer 19

1. Homozygous Dominant: Both alleles are the same and dominant. Dominant is expressed.
2. Homozygous Recessive: Both alleles are the same and recessive. Recessive is expressed.
3. Heterozygote: Dominant allele and Recessive allele. The dominant is expressed but the recessive allele is still carried.

Question 20

BB

Answer 20

Homozygous Dominant

Question 21

bb

Answer 21

Homozygous Recessive

Question 22

Bb

Answer 22

Heterozygote

Question 23

If 2 heterozygotes mate what are the chances of transmission of a recessive disorder to their child, chance of carrier child, chance of a “normal” child?

Answer 23

25% chance of an affected child.
50% chance of a carrier child.
25% chance of a “normal” child.

Question 24

When do most autosomal recessive disorders occur?

Answer 24

When heterozgotes (carriers) mate. Because carriers don’t express the trait they do not know they have it.

Question 25

What are 3 examples of autosomal recessive disorders?

Answer 25

1. Cystic Fibrosis (whites 25-40% carriers). Recessive gene causes thick exocrine secretions which impair lung and pancreatic function (trouble breathing and digesting).
2. Sickle Cell Anemia (blacks 25-40% carriers). Hemolytic anemia caused by fragile and abnormally shaped RBCs. RBCs can’t carry O2 well.
3. Phenylketonuria (PKU). Missing enzyme prevents metabolization of phenylalanine, a common amino acid. It can cause CNS damage to newborns.

Question 26

PKU

Answer 26

Phenylketonuria. Normally Phenylalanine (amino acid) gets metabolized by an enzyme which turns it into tyrosine and turns that into melanin pigment. In someone with PKU the Phynylalanine (amino acid) doesn’t get metabolized because the enzyme is missing. So instead of turning into Tyrosine there is a Phenylalanine and Derivatives build up which causes toxicity affecting brain development.

Question 27

GENETIC DEFECTS, BUT SEX LINKED INHERITANCE:

What usually happens in a sex-linked inheritance?

Answer 27

Usually the defective allele is transmitted from mother to son on the X of the 23rd chromosome.

Question 28

Example of sex-linked inheritance…

Answer 28

Hemophilia.

Question 29

Sex-linked inheritance:
Carrier Mother with Normal Father…what are the chances for their children?
Affected Father with Normal Mother…what are teh chances for their chidren?
Affected Father with Carrier Mother…what are the chances for their children?

Answer 29

Carrier Mother with Normal Father =
25% normal boy
25% normal girl
25% carrier girl
25% affected boy
Affected Father with Normal Mother = 
50% carrier girl
50% normal boy
Affected Father with Carrier Mother = 
25% normal boy
25% carrier girl
25% affected boy
25% affected girl

Question 30

CONGENITAL DEFECTS:

What is a congenital defect?

Answer 30

A birth defect or disease that is present at birth but NOT due to genetics.

Question 31

What causes congenital defects?

Answer 31

By anything that interferes with intrauterine development like poor blood flow and oxygen delivery, maternal viral infection, and drugs taken by the mother.

Question 32

What is a Thalidomide Baby?

Answer 32

A drug defect. During the 1st trimester the drug Thalidomide was used to help make morning sickness go away. Later found out this caused birth defect of the limbs.

Question 33

Can a child born with a birth defect pass the defect on to his/her own child?

Answer 33

NO!