L19: Numerical Chromosome anomalies Flashcards
1
Q
What are the main types of mutation
A
- single gene disorders : autosomal dominant and recessive and x linked
- Chromosome
- mitochondrial
- multifactorial
2
Q
What is the classification of chromosomal anomalies
A
- numerical
- structural
- cell lines
3
Q
What does numerical chromosomal anomalies include
A
- aneuploidy: trisomy and monosomy
- polyploidy: trisomy
4
Q
What does structural chromosomal anomalies include
A
- translocation: reciprocal and robertsonian
- deletion
- duplication
- inversion
5
Q
What does cell lines include
A
Mosaicism
6
Q
What is the most common numerical disorders
A
Down’s syndrome Patau syndrome Edwards syndrome Klinefelter syndrome Turner syndrome
7
Q
What are the 3 clauses of Down’s syndrome
A
- trisomy 21
- robertsonian translocation
- somatic mosaicism
8
Q
How does trisomy 21 occur to give Down syndrome
A
- non disjunction occurs in meiosis 1 or 2 in eggs of the mother
9
Q
Why does non disjunction occur in eggs but not sperms to give trisomy 21
A
- oocytes are a stock of egg
- each month one oocyte is released and completes meiosis 1
- as the maternal age increases the egg undergoes wear and tear to the spindle fibres
- at fertilisation when meiosis 2 is occurring the spindles cannot separate the chromosomes
- this results in trisomy 21
10
Q
What is patau syndrome
A
Trisomy 13
11
Q
What is edwards syndrome
A
Trisomy 18
12
Q
What is Klinefelter syndrome
A
47, XXY
13
Q
What is turners syndrome
A
45,X
14
Q
What is triploidy
A
When there are 69 chromosomes
15
Q
Is autosomal monosomy or sex chromosome anamolies the worst
A
Autosomal monosomy
