Chromosomal disorders

Question 1

Describe chromosome abnormality (or abberations)

Answer 1

Any deviation from the normal karyotype is known as a chromosome abnormality.
The most severe chromosome disorders are caused by the loss or gain of whole chromosomes, which can affect hundreds, or even thousands, ofgenesand are usually fatal.
While some chromosome abnormalities are harmless, some are associated with clinical disorders.​

Chromosome abnormalities usually occur when there is an error in cell division resulting in cells with too few or too many copies of a chromosome, during meiosis​

Most chromosome abnormalities originate in the egg or sperm but some happen during embryo development or are inherited from a parent.​

Chromosome abnormalities that originate in the gametes(egg or sperm) are present in every cell of the body.

Question 2

What is Cytogenetics?

Answer 2

Cytogenetics is a branch of genetics that is concerned with how the chromosomes relate to cell behavior, particularly to their behavior during mitosis and meiosis.​

Techniques used include karyotyping, analysis of G-banded chromosomes, as well as molecular cytogenetics such as fluorescent in situ hybridization (FISH) and comparative genomic hybridization (CGH).​

Question 3

What are the chromosome aberrations (abnormalities) four major criteria?

Answer 3

1. Intrauterine and postnatal growth retardation​
2. a pattern of dysmorphic signs, especially of facies, genitalia and distal limbs​
3. malformations, often multiple​
4. impaired mental development/mental deficiency