Chromosomal Disorders Flashcards
3 types of chromosomal abnormalities
Aneuploidy, rearrangements, deletions/duplications.
What does aneuploidy mean?
Presence of an abnormal number of chromosomes in a cell. Too many/few chromosomes.
Name 3 different types of rearrangements.
Translocations (balanced and unbalanced), inversions, complex chromosome rearrangements (CCRs).
What are Roberstonian translocations?
Robertsonian translocation (ROB) is the most common form of chromosomal rearrangement where the participating chromosomes break at their centromeres and the long arms fuse to form a single, large chromosome with a single centromere.
What is a reciprocal translocation?
Reciprocal translocations are usually an exchange of material between non-homologous chromosomes.
2 syndromes associated with chromosome imbalances (deletions/duplications)
Prader Willi Syndrome, Angelman Syndrome
Name 3 monogenic hereditable diseases.
Spinal muscular atrophy (SMA), cystic fibrosis (CF), Duchenne Muscular Dystrophy (DMD)
Name a non-invasive blood sampling method
Peripheral maternal blood sampling. Analysis of fetal DNA which circulates freely in the maternal blood. Maternal blood is sampled by venipuncture.
Name a genetic testing method and explain its process.
A technique used in cytogenetics to produce a visible karyotype by staining condensed chromosomes. Confirmation of an aCGH follow-up.
What are microsatellites, and what are they used for?
Repetitive DNA sequences made up of 2-10 base pairs. Used in aCGH to identify chromosomes 13, 18 and 21.
What is the difference between balanced and unbalanced translocations?
Translocations can be balanced (in an even exchange of material with no genetic information extra or missing, and ideally full functionality) or unbalanced (where the exchange of chromosome material is unequal resulting in extra or missing genes).
What are the 4 different movements for the sections of a chromosome?
Deletion. Duplication. Inversion. Translocation.
A deletion in part of the chromosome results in…
Cri du chat syndrome.
What is Prader Willi Syndrome?
Prader-Willi syndrome is a rare genetic condition that causes a wide range of physical symptoms, learning difficulties and behavioural problems. It’s usually noticed shortly after birth.
What is Angelman Syndrome?
A genetic disorder that mainly affects the nervous system. Symptoms include a small head and a specific facial appearance, severe intellectual disability, developmental disability, speaking problems, balance and movement problems, seizures, and sleep problems.
