Consanguinity And Cytogenetics Flashcards
2 types of patterns associated with lethal alleles
- Recessive lethal alleles
2. Present/expressed in combination
When will a person with a recessive lethal allele not show the phenotype?
What is the % of this lethal equivalent?
When the person remains heterozygous for the loci
50%
Lethal allele groups- a person can have several of the alleles of a lethal allele group, but it will not be expressed if
It is not expressed at the homozygous level
On average, how many lethal equivalents does a person carry
3-8 (5)
Methemoglobinemia:
- What is methemoglobin
- Characteristic of methemoglobin? (2)
- How will blood appear in people with this condition?
- Another name for this condition
- Heme iron is oxidized from Fe2+ to Fe3+
- No affinity for oxygen; stays in deoxygenated form
- Blood has a bluish-chocolate brown color
- Chocolate cyanosis
How to tell if blood is blue due to methemoglobinemia vs lack of oxygen?
Lack of oxygen blood will immediately turn red when exposed to air, methemoglobinemia blood will not
4 oxidative stressors that will cause acquired methemoglobinemia
Certain drugs, antibiotics, caine anesthetics, and compounds containing nitrates
Infants under 6 months are more prone to methemoglobinemia caused by?
Why does this affect babies more than adults?
Elevated nitrates in drinking water/certain foods
Enzymes used to protect against methemoglobinemia have not yet reached adult levels
Causes of congenital methemoglobinemia:
- Deficiency of what 3 enzymes/what do they do
- What 2 types of abnormal hemoglobin?
- 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) - HbH and HbM
- Which of the previously mentioned enzyme is defective in the kentucky blue people
- What accumulates in the blood
- Is the enzyme completely devoid or deficient?
- NADH-methemoglobin reductase
- Methemoglobin
- Deficient
Methemoglobin in blood:
- Taut or relaxed state
- Oxy or deoxy
- __ 2,3 BPG levels
- Treatment and side effect of this treatment
- Taut
- Deoxy
- Increased
- Methylene blue; urine turned blue
Von Hippel-Lindau syndrome:
- Mutation in what gene
- One result of this condition
- ~20% of people with this syndrome have tumor of __
- Symptom? Why?
- Tumor suppressor gene
- Pheochromocytomas
- Adrenal gland
- Explosive temper; excess production of adrenaline
Lynch syndrome:
- What is it
- Defect in what genes
- Another name
- Prevalent where in america?
- Hereditary nonpolyposis colorectal cancer
- Mismatch repair genes
- American founder mutation
- Kentucky
- What is euploidy
2. Number of chromosomes in humans of haploid, diploid, triploid, and tetraploid
- When a cell has a multiple of 23 chromosomes
2. 23, 46, 69, 92
Triploidy:
- How many chromosomes
- Usually a result of
- Death occurs quickly due to defects of what 2 systems
- 69
- 2 sperm fertilizing the same egg
- Heart and CNS
Tetraploidy
- How many chromosomes
- Usually die when
- 92
2. Before birth
- What is aneuploidy
- Monosomy?
- Trisomy?
- Deviation from the euploid number of chromosomes (loss or gain of specific chromosomes)
- One copy of a specific chromosome is present
- Three copies of a specific chromosome is present
- There is only one monosomy compatible with life - what is it
- Which 3 trisomies can potentially survive
- Which type of trisomies may even appear normal?
- Turner syndrome - only 1 X chromosome
- 13, 18 and 21
- Sex chromosome trisomies
So based on the previous, does the body tolerate extra genetic information or loss of genetic information better?
Extra genetic information
What are monosomies and trisomies caused by
Nondisjunction of chromosomes during meiosis
- How will a meiosis I nondisjunction appear?
- How will a meiosis II nondisjunction appear?
- This both contribute to what kind of disorder
- Which is more serious
- What increases risk of nondisjunction? In meiosis I or II?
- All chromosomes go to one cell, other cell has no copy of chromosome
- Ends with 2 normal cells, as well as one that has no genetic information and one that has double
- Trisomy
- Meiosis I nondisjunction
- Increased maternal age; I
Trisomy 21:
- Causes?
- Most genetic cause of?
- Recap: what is the most common hereditary cause of the answer to 2. ?
- Down syndrome
- Mental retardation
- Fragile X
So Fragile X = hereditary
Down syndrome= genetic
Down syndrome symptoms
~what type of cancer are they more prone to
Short, characteristic face, congenital heart defects, respiratory infections, increased risk of leukemia, alzhemiers by 40
Trisomy 18:
- Causes what syndrome
- When do they usually die
- Symptoms (4)
- Edwards syndrome
- First year of life
- Clenched fist, rocker bottom feet, prominent occiput, small mouth/ears/size overall
Trisomy 13:
- Causes what syndrome
- Symptoms (3)
- Patau
2. Oral-facial clefts, microphtalmia (small eyes), polydactyly
- What is sex chromosome aneuploidy
2. Why are they less severe than autosomal aneuploidies?
- Increased or decreased amount of sex chromosomes
2. At least one X chromosome is required for survival
Klinefelter syndrome:
- What is the sex chromosome defect (what are they instead of XY or XX)
- Are they male or female
- Symptoms
- XXY
- Male
- Atrophy of seminiferous tubules/testes (sterile), long arms/legs, lack of male secondary sex characteristics, breast development, low IQ
Turner syndrome:
- Type of disease
- Some variation among survivors of what defines this disease- name the 3
- Symptoms
- Monosomy
- Either only one X chromosome, missing part of one of the X chromosomes, or are mosaics
- Short, webbed neck, lymphedema, widely spaced nipples, sterile due to gonadal dysgenesis
XYY males
- How do they look
- Other symptom?
- Usually normal males, but very tall
2. Mild social problems
XXX females
1. Symptom
- Essentially normal (most are never diagnosed) increased probability of psych problems (schizophrenia)
