MCBG S12 Chromosome Mutations Flashcards
(37 cards)
What is cytogenetics?
The study of the genetic constitution of cells through the visualisation and analysis of chromosomes.
Why do we do cytogenetic analysis?
- Provide diagnosis and prognosis of clinical problems
- Better clinical management
- Assess reproductive risks.
- Prenatal diagnosis
What are the 2 main reasons for referral to cytogenetics department?
People with abnormalities since birth
People with acquired abnormalities as part of the disease proves
What are 2 methods of prenatal diagnosis?
Chorionic villus sampling
Amniocentesis
What is the risk of prenatal diagnosis?
Miscarriage risk.
What is involved in prenatal diagnosis?
Needed guided under US - invasive methods.
Biochemical markers tested for.
What are some birth defect types?
Dysmorphism Mental retardation Congenital malformations Developmental delay Specific syndromes.
What testing method is mainly used in cytogenetic analysis?
Karyotyping
What is the karyotyping nomenclature?
Number of chromosomes, sex Complement and structure changes seperated by commas
NO SPACES
What is mosaicism?
2 cell lineages/populations in an individual
What causes anueploidy?
Non-disjunction in Meiosis.
What is polyploidy?
Gain of haploid set of chromosomes.
What is the most common cause of polyploidy?
Polyspermy
What extra chromosomes confer viability of life, in terms of anueploidy?
13
18
21
What missing chromosomes still allow for viability of life and why?
X chromosomes
What are the symptoms of trisomy 21, Down syndrome?
Hypertonic
Characteristic facial features
Intellectual disability
Heart defects
What are the symptoms of trisomy 18 Edward syndrome?
Smaller lower jaw Prominent occiput Lower set ears Rocker bottom feet Over-lapping fingers
SPLRO
What are the symptoms of trisomy 13, Patau syndrome?
Polydactyl
Holoproscencephaly - multiple cleft palates
Die in neonatal period
What are symptoms of Turner syndrome?
Puffy feet Redundant skin and back of neck Short stature Heart defects Mild learning difficulties Neck webbing Infertility
Trisomic concept is may be rescued from trisomy 21 if _______ ____ occurs during division getting rid of the extra chromosome 21.
Anaphase lag
Name some types of cytogenetic structural abnormalities.
Translocations Inversions Duplications Deletion Insertions Rings Isochromosomes
What is a balanced translocation?
Translocation in which no chromosome material has been lost or gained.
When can a balanced translocation cause a problem?
When they come to have children. Offspring can inherit an unbalanced form of the translocation.
What is an unbalanced translocation?
When there has been loss or gain of genetic material as a result of a translocation
