Genomics and chromosomal diseases Flashcards
What is genomics?
The study of the whole genome of organisms. (It incorporates elements form genetics.) Includes both heritable mutations/diseases and mutations/diseases occuring “de novo”.
What is chromatin?
DNA and packaging proteins.
What is meant by exome?
The exome includes all the exons in the genome (= all the genes.)
What is copy number?
The number of copies of a particular gene in the genome of an individual.
Name some laboratory tests used in chromosomal analysis.
Traditional (G-band) chromosomal analysis.
FISH.
Quantitative Fluorescence - Polymerase Chain Reaction (QF-PCR).
Chromosomal microarray.
Copy number variations in exome sequencing.
True or false: Mitosis gives rise to two diploid cells.
True. (The daughter cells are identical diploids.)
True or false: Meiosis gives rise to four genetically identical daughter cells.
False. Meiosis gives rise to four genetically distinct daughter cells.
At which times are the chromosomes in cells visible?
The chromosomes are only visible during cell division.
At which stage of cell division are the cells arrested when doing a standard G-band chromosome analysis.
Metaphase: The stage in which the chromosomes are in their second-most coiled and condensed form.
What is a karyogram?
A graphical presentation of a person’s chromosomes.
What is meant by karyotype?
A person’s individual collection of chromosomes, commonly used to described/identify abnormal structures or numbers of chromosomes.
What is the normal karyotype for a female? What is the normal karyotype for a male?
46, XX is the normal karyotype for a female.
46, XY is the normal karyotype for a male.
What laboratory test for chromosomal analysis is referred to as a rapid test/”hurtigtest” for aneuplodies?
Qualitative Fluorescence - Polymerase Chain Reaction (QF-PCR).
What is meant by aneuploidy?
The over- or under-representation of one (or a few) chromosome(s) or one (or a few) chromosomal segment(s).
For which laboratory test for chromosomal analysis is the following statement true: “The test only detects unbalanced abnormalities”?
Chromosomal microarrays.
What are some indications for conducting a standard G-band chromosome analysis?
Three or more spontaneous abortions.
Suspected structural chromosomal aberration.
Suspected sex chromosome abnormality (growth, pubertal development).
What are some indications for conducting a QF-PCR?
Prenatal diagnostics.
Learning difficulties.
What are some indications for conducting a SNP-array?
Intellectual disability, severe autism.
Major or several minor congenital malformations.
What is the normal number of chromosomes in gametes?
Gametes are haploids and normally have 23 chromosomes.
What is non-disjunction?
The failure of homologous chromosomes or sister chromatids to separate properly during cell division.
There are three forms of non-disjunction:
1) Failure of separation of homologous chromosomes during meiosis 1
2) Failure of separation of sister chromatids during meiosis 2
3) Failure of separation of sister chromatids during mitosis.
What is Klinefelter syndrome?
Over-representation of the X-chromosome in males. Karyotype 47, XXY (or 48 XXXY and so on …).
What are some clinical features associated with XYY syndrome?
Tall stature.
Acne.
Learning difficulties (are more common than in the general population. Delays in speech and language development may occur.)
What is the karyotype for Turner syndrome? What are some clinical features associated with Turner syndrome?
45, X.
Short stature, webbed neck, shield chest, underdeveloped breasts, widely spaced nipples, rudimentary ovaries, infertility.
What are the three most commmon trisomies?
Trisomy 21 (Down’s syndrome), trisomy 13 (Patau syndrome) and trisomy 18 (Edwards syndrome).
