Consanguinity And Cytogenetics

Question 1

2 types of patterns associated with lethal alleles

Answer 1

1. Recessive lethal alleles

2. Present/expressed in combination

Question 2

When will a person with a recessive lethal allele not show the phenotype?

What is the % of this lethal equivalent?

Answer 2

When the person remains heterozygous for the loci

50%

Question 3

Lethal allele groups- a person can have several of the alleles of a lethal allele group, but it will not be expressed if

Answer 3

It is not expressed at the homozygous level

Question 4

On average, how many lethal equivalents does a person carry

Answer 4

3-8 (5)

Question 5

Methemoglobinemia:

1. What is methemoglobin
2. Characteristic of methemoglobin? (2)
3. How will blood appear in people with this condition?
4. Another name for this condition

Answer 5

1. Heme iron is oxidized from Fe2+ to Fe3+
2. No affinity for oxygen; stays in deoxygenated form
3. Blood has a bluish-chocolate brown color
4. Chocolate cyanosis

Question 6

How to tell if blood is blue due to methemoglobinemia vs lack of oxygen?

Answer 6

Lack of oxygen blood will immediately turn red when exposed to air, methemoglobinemia blood will not

Question 7

4 oxidative stressors that will cause acquired methemoglobinemia

Answer 7

Certain drugs, antibiotics, caine anesthetics, and compounds containing nitrates

Question 8

Infants under 6 months are more prone to methemoglobinemia caused by?

Why does this affect babies more than adults?

Answer 8

Elevated nitrates in drinking water/certain foods

Enzymes used to protect against methemoglobinemia have not yet reached adult levels

Question 9

Causes of congenital methemoglobinemia:

1. Deficiency of what 3 enzymes/what do they do
2. What 2 types of abnormal hemoglobin?

Answer 9

1. NADH methemoglobin reductase (diaphorase I) - converts Fe3+ back to Fe2+
   Pyruvate kinase- impaired production of NADH
   G6P dehydrogenase- impaired production of NADPH (HMP shunt problems)
2. HbH and HbM

Question 10

1. Which of the previously mentioned enzyme is defective in the kentucky blue people
2. What accumulates in the blood
3. Is the enzyme completely devoid or deficient?

Answer 10

1. NADH-methemoglobin reductase
2. Methemoglobin
3. Deficient

Question 11

Methemoglobin in blood:

1. Taut or relaxed state
2. Oxy or deoxy
3. __ 2,3 BPG levels
4. Treatment and side effect of this treatment

Answer 11

1. Taut
2. Deoxy
3. Increased
4. Methylene blue; urine turned blue

Question 12

Von Hippel-Lindau syndrome:

1. Mutation in what gene
2. One result of this condition
3. ~20% of people with this syndrome have tumor of __
4. Symptom? Why?

Answer 12

1. Tumor suppressor gene
2. Pheochromocytomas
3. Adrenal gland
4. Explosive temper; excess production of adrenaline

Question 13

Lynch syndrome:

1. What is it
2. Defect in what genes
3. Another name
4. Prevalent where in america?

Answer 13

1. Hereditary nonpolyposis colorectal cancer
2. Mismatch repair genes
3. American founder mutation
4. Kentucky

Question 14

1. What is euploidy

2. Number of chromosomes in humans of haploid, diploid, triploid, and tetraploid

Answer 14

1. When a cell has a multiple of 23 chromosomes

2. 23, 46, 69, 92

Question 15

Triploidy:

1. How many chromosomes
2. Usually a result of
3. Death occurs quickly due to defects of what 2 systems

Answer 15

1. 69
2. 2 sperm fertilizing the same egg
3. Heart and CNS

Question 16

Tetraploidy

1. How many chromosomes
2. Usually die when

Answer 16

1. 92

2. Before birth

Question 17

1. What is aneuploidy
2. Monosomy?
3. Trisomy?

Answer 17

1. Deviation from the euploid number of chromosomes (loss or gain of specific chromosomes)
2. One copy of a specific chromosome is present
3. Three copies of a specific chromosome is present

Question 18

1. There is only one monosomy compatible with life - what is it
2. Which 3 trisomies can potentially survive
3. Which type of trisomies may even appear normal?

Answer 18

1. Turner syndrome - only 1 X chromosome
2. 13, 18 and 21
3. Sex chromosome trisomies

Question 19

So based on the previous, does the body tolerate extra genetic information or loss of genetic information better?

Answer 19

Extra genetic information

Question 20

What are monosomies and trisomies caused by

Answer 20

Nondisjunction of chromosomes during meiosis

Question 21

1. How will a meiosis I nondisjunction appear?
2. How will a meiosis II nondisjunction appear?
3. This both contribute to what kind of disorder
4. Which is more serious
5. What increases risk of nondisjunction? In meiosis I or II?

Answer 21

1. All chromosomes go to one cell, other cell has no copy of chromosome
2. Ends with 2 normal cells, as well as one that has no genetic information and one that has double
3. Trisomy
4. Meiosis I nondisjunction
5. Increased maternal age; I

Question 22

Trisomy 21:

1. Causes?
2. Most genetic cause of?
3. Recap: what is the most common hereditary cause of the answer to 2. ?

Answer 22

1. Down syndrome
2. Mental retardation
3. Fragile X

So Fragile X = hereditary
Down syndrome= genetic

Question 23

Down syndrome symptoms

~what type of cancer are they more prone to

Answer 23

Short, characteristic face, congenital heart defects, respiratory infections, increased risk of leukemia, alzhemiers by 40

Question 24

Trisomy 18:

1. Causes what syndrome
2. When do they usually die
3. Symptoms (4)

Answer 24

1. Edwards syndrome
2. First year of life
3. Clenched fist, rocker bottom feet, prominent occiput, small mouth/ears/size overall

Question 25

Trisomy 13: 1. Causes what syndrome 2. Symptoms (3)

Answer 25

1. Patau | 2. Oral-facial clefts, microphtalmia (small eyes), polydactyly

Question 26

1. What is sex chromosome aneuploidy | 2. Why are they less severe than autosomal aneuploidies?

Answer 26

1. Increased or decreased amount of sex chromosomes | 2. At least one X chromosome is required for survival

Question 27

Klinefelter syndrome: 1. What is the sex chromosome defect (what are they instead of XY or XX) 2. Are they male or female 3. Symptoms

Answer 27

1. XXY 2. Male 3. Atrophy of seminiferous tubules/testes (sterile), long arms/legs, lack of male secondary sex characteristics, breast development, low IQ

Question 28

Turner syndrome: 1. Type of disease 2. Some variation among survivors of what defines this disease- name the 3 3. Symptoms

Answer 28

1. Monosomy 2. Either only one X chromosome, missing part of one of the X chromosomes, or are mosaics 3. Short, webbed neck, lymphedema, widely spaced nipples, sterile due to gonadal dysgenesis

Question 29

XYY males 1. How do they look 2. Other symptom?

Answer 29

1. Usually normal males, but very tall | 2. Mild social problems

Question 30

XXX females | 1. Symptom

Answer 30

1. Essentially normal (most are never diagnosed) increased probability of psych problems (schizophrenia)