| What is karyotyping | Analysis of chromosomes to detect any abnormalities
Karyotype --> complete set of chromosomes of a person |
| What are source cells for karyotyping | Bone marrow ( luekemia only )
Blood
Solid tissues
Amniotic fluid
Chorion villus sampling |
| What are the different types of chromosomes | Metacentric
Sub-metacentric
Acrocentric ( D and G ) |
| What are some indications for karyotyping | Recurrent fetal loss
Birth defects
Family history
Materanal age is over 35
Leukemia
Abnormal sexual development
Infertility |
| What are some benefits for karyotyping | Accurate diagnosis and prognosis
Better management plan
Understanding the risk of reproduction for carriers
Possible termination of inflicted pregnancies |
| What is polyploidy | This is when there is a multiple of the haploid number and greater then the diploid number e.g. 3n 69,XXX
This is because of more than one sperm fertilising a single egg |
| What is Aneuploidy | This is when it is not a multiple of the haploid
Monosomy --> loss of 1 homologous chromosome
Trisomy --> gain one homologous chromosome
Can happen in both sex chromosomes and others |
| What is anaphase lag | Some chromosomes can be left behind due to defects in the mitotic spindle fibres |
| What do you get if there is non-disjunction at Meiosis I | 2( N+1 ) and 2 ( n-1 ) |
| Non-disjunction at Meiosis II | ( n+1 ) ( n-1 ) (n ) ( n ) |
| What is Trisomy 21 | Down syndrome
47,XX,+21
Clinical features :
Intellectual disability
CHD
Hearing/eye disorders
Haemotological malignancies
Infertility
Hypothyroidism |
| Trisomy 18 | Edwards Syndrome
47,XX,+18
More common in girls
Kidney and Heart Problems
Learning difficulties
Growth retardation
Breathing problems |
| Trisomy 13 | Patau's syndrome
47,XY,+13
More common in boys
Multiple abnormalities
Severe learning difficulties
Polydactyly |
| What is Turner's syndrome | Monosomy
45,X
X chromosome inactivation
Short stature
Infertility
Webbed neck
Heart defects |
| Triple X syndrome? | 47,XXX
Tall stature
Small head
Motor delayed skills
Seen after puberty |
| Double Y syndrome | 47,XYY
Often not diagnosed
Tall stature
Lower IQ
Normal testorsterone and fertile
Behavioral problems |
| Klinnefelter syndrome | 47,XXY
Decrease testesterone
Increase breast tissue
Language and reading impairment |
