Flashcards in Chromosomal Aberrations Deck (53):
What are chromosomal aberrations?
Abnormalities in structure and number of chromosomes
What is meant by the term aneuploid?
uneven number of chromosomes (e.g. 1 or 3)
What are the three trismonies that can be observed in practice?
A person with only one X chromosome and no Y has what syndrome?
What is the genotype of someone with Klinefelter syndrome?
What are the two ways in which structural chromosomal abnormalities occur?
Non-homologus end joining
Which are generally more severe: duplications or deletions?
What is CRI-Du-Chat syndrome?
Arises from a deletion on chromosome 5
What is Di George syndrome?
microdeletion on chromosome 22. Results are very variable but include:
What is an insertion?
Taking a part of one chromosome and inserting it into another
What is a translocation?
Taking a part of one chromosome and attaching it onto the end of another
A translocation between chromosome 9 and 22 produces what disease?
The Philadelphia chromosome--Ber/Abl protein---chronic myeloid leukemia
What is a Robertsonian translocation?
When two chromosomes simultaneously exchange material via translocation. Results in the longs pairing, and the shorts pairing
How do inversions happen?
When a chromosome is damaged and the broken fragment is attached upside down
True or false: inversions of chromosomes are almost always lethal for the carrier.
True or false: inversions of chromosomes are almost always lethal for the carrier's offspring. Why/why not?
True, because the inverted regions have to loop around in meiosis to pair with the homologous chromosome. If crossover occurs, then this is a translocation
What is a balanced alteration?
A chromosomal rearrangement that does not change the amount of DNA in the affected cell
What is an unbalanced alteration?
A chromosomal rearrangement that changes the amount of DNA in the affected cell
True or false: carriers of balanced alterations are usually aware of their condition?
True or false: carriers of balanced alteration usually produce viable offspring
What is karyotyping?
Studying the composition of the chromosomes in a cell
What are the six indications for examining a karyotype?
Problems of early growth/development
Still birth/neonatal death
Pregnancy with advanced maternal age
Family h/o chromosomal aberrations
Out of 10000 pregnancies, how many live births are there? Spontaneous abortions?
Out of 10000 pregnancies, how many will have normal chromosome? Abnormal?
9200 normal (92%), 800 abnormal
Of the 8500 live births, how many children will have down syndrome?
A deletion of chromosome 5 results in what disease? Symptoms?
Cri-du-chat syndrome. MR, microcephaly, micrognathia, heat defects, cat-like-cry
A microdeletion on chromosome 22 results in what disease? Symptoms?
Di George syndrome. Congenital heart defects, MR, cleft palate, immunodeficiency
A traslocation between chromosome 9 and 22 produces what disease/new chromosome?
Philadelphia chromosome produced, chronic myeloid leukemia due to overexpression of Abl1 gene due to translocation to Bcr. (Abl/Br tyrosine kinase)
What type of crossover occurs when two entire arms are switched?
What is the term that describes the translocation of a chromosome and a reinsertion of the gene backwards? When is this a problem?
Problem for individual's offspring, not usually individual them self.
What are the three things to look for in a pedigree that is suggestive of chromosomal inheritance?
1. MR, multiple symptoms
2. Multiple spontaneous abortions
How do chromosomal abberrations result in CA?
Genomne instability deletes tumor suppressors/ amplifies oncogenes
Loss of cell cycle control
What is the karyotype for Turner's syndrome?
What is the karyotype for Klinefelter syndrome?
What is the karyotype for Edwards, patau, and down syndomes?
47, 13 = Patau
47, 18 = Edwards
47, 21 = Down
Of 10000 pregnancies, how many balanced rearrangements will there be? How many of these will spontaneously abort? How many survive?
Of 10000 pregnancies, how many unbalanced rearrangements will there be? How many of these will spontaneously abort? How many survive?
Of 10000 pregnancies, how many will have normal chromosomes? How many of these will spontaneously abort? How many survive?
9200/10000 will have normal chromosomes
Of 10000 pregnancies, how many will have ABnormal chromosomes? How many of these will spontaneously abort? How many survive?
800/10000 will have abnormal chromosomes
Of 10000 pregnancies, how many will have extra X chromosomes? How many of these will spontaneously abort? How many survive?
Of 10000 pregnancies, how many will have Down syndrome? How many of these will spontaneously abort? How many survive?
What percentage of children are born with recognizable birth defects?
What is the rate of child death due to birth defects? To premature birth?
Give data for HPNOC (my acronym)?
Heart defects 1/100-1/200
Pyloric stenosos 1/300
Neural tube defects 1/1000
Orofacial clefts 1/700 - 1/1000
What percent of birth defects have complex inheritance?
What percent of births are caused by single chromosomal defects?
What percent of birth defects are caused by single GENE mutations?
What percent of birth defects are caused by non-genetic factors?
Chromosomal and genomic disorders affect what percent of the population?
Single gene disorders affect what percent of the population?
Disorders with multifactorial inheritance affect what percent of the population?
What is the prevalence of Down? Edward? Patau?
1/800 for Down
1/8000 for Edward
1/25000 for patau