Chromosomal Aberration

 Chromosomal Aberration

Chromosomal Aberrations changes in chromosome structure or number.

Chromosomal Aberrations; changes in chromosomal number (gain and loss) and changes in structure (dilation, inversion, exchanges)

Types of chromosomal Abnormalities

1. Numerical abnormalities

2. Structural abnormalities

1. Numerical abnormalities

Aneuploidy

Polyploidy

Triploidy

Tetraploidy

Mosaicism

2. Structural abnormalities

Deletion

Duplication

Inversion

Ring

Isochromosome

Translocation

Etiology of chromosomal Aberrations

1. Error in cell division (mitosis)

2. Exposure to substance cause teratogenic

3. Changes in chromosomal structure

4. Error in cell division

5. Maternal age

6. Environment

7. Failure of whole chromosome to separate during meiosis.

8. Inherited

Clinical manifestations

1. Abnormally shaped head

2. Cleft lip (opening in lip or mouth)

3. Mental and physical element

4. Intellectual disability/ Learning disability

5. Inherited disease such as; down syndrome, Turner syndrome

6. Infertility

7. Eye movement

Laboratory Investigation for chromosomal Aberrations

1. Meta phase arresting substance; harvested, stained and metaphase cells or analyze microscopcally for the presence of chromosomal Abberrations.

2. Chromosome Aberration analysing test invitro

3. In vitro mammalian chromosome Aberration test

4. Chromosome Aberration assay

5. Fetal echocardiography

6. Radiography

7. Ultrasound

Screening

1. Maternal unconjugated estriol; produced by placenta

Decrease in down syndrome

2. Maternal serum Human HCG 

Increase in Down syndrome

3. Maternal Inhibin A level (by placenta corpus luteum); made by placenta during pregnancy

Increase in Trisomy 21

4. Separation of fetal cells from maternal blood

For example; FISH (Fluorescent insitu hybridization) to diagnose aneuploidy.

5. Alpha- Feto protein (AFP)

6. Embryoscopy 

7. Fetal tissue sampling

Aminocentesis

Chorionic villus sampling

Cordocentesis (Percutaneous umbilical cord blood sampling).

8. Prenatal or antenatal test

1. Aminocentesis (12-20 weeks)

2. Chorionic villus sampling (8-12 week)

3. Percutaneous umbilical cord blood sampling (fetal blood sampling); performed after 20 weeks

4. Early ultrasound

5. Cordocentesis

6. HCG test; produce by placenta

7. Alkali- denaturation test (APT test)

8. Prenatal cell free Cf DNA screening (non- invasive prenatal testing)

9.  Carrier screening

Management

1. Reducing risk of chromosomal Abnormality

2. Genetic Counseling

3. Manage of inherited disease condition such as;

Hemochromatosis

Thalassemia

Down syndrome (Trisomy 21)