GENETIC COUNSELLING

By- Shireen Fathima 206

Genes-Genes are the units of heredity.

-They affect development and function, both normal and abnormal.

Genetics Genetics is defined as a branch of

science which is concerned with the transmission of characteristics from parents to offsprings.

Genetic disorderThe genetic transmission of a

particular disorder from parents to offsprings.

Counselling

Counselling is consultation, mutual interchange of opinions, deliberating together. (Webster’s dictionary)

A process in which the counsellor assists the counselee to make interpretations of facts relating to a choice, plan or adjustments which he needs to make. (Smith 1955)

Genetic Counselling

American society of human genetics defines, ‘’Genetic counselling as a communication process which deals with the human problems associated with the occurance or risk of a genetic disorder in a family.

This term was proposed by Sheldon Reed in 1947

Provide concrete, accurate information about inherited disorders.

Provides information about prognosis and follow up.

Provides information on risks of developing and transmitting the disorder.

Discuss ways in which disease can be prevented

Reassure people who are concerned

Allow people who are affected by inherited disease to make informed choices about future reproduction

Help family in decision making process

Explaining alternatives to reduce the risk of genetic disorders.

Providing psychological support

Who does genetic counselling?Done by a team comprising of:

Medical specialistGenetic counselorAdditional members like family

physicians, social workers, religious support persons etc

Indications for genetic counsellingAdvanced maternal age  

All ages 1 in 650

Age 20 1 in 1540

Age 25 1 in 1350

Age 30 1 in 895

Age 35 1 in 350

Age 40 1 in 100

Age 45 1 in 20

Appropriate risk for trisomy 21 at birth by maternal age.

Age 20 1 in 525

Age 25 1 in 475Age30 1 in 380Age 36 1 in 180Age 38 1 in 105Age 40 1 in 65Age 42 1 in 40Age 45 1 in 20

Maternal age and birth rates for children with chromosomal abnormalities- Approximate

Known or suspected hereditary condition in the family

ConsanguinityRecurrent spontaneous abortionsA foetus or child with birth

defectsMiscarriages

Process of genetic counsellingMedical diagnosis- Karyoptyping, analysis of blood,

urine, cultured cells.-Present and past relevant history-

Family history of siblings and relatives. If there is any member havinf same problem.

-Enquiry about consanguinity as it increases chances.

Pedigree AnalysisComplete four generation family pedigree.

Reliability to be checked.

Ask for abortions, illegitimate births, miscarriages, still births and mildly affected relatives.

Types of genetic counselling

Prospective counselling

Retrospective counselling

Options to refrain from childbearing risks

Abortion

In vitro fertilization

Prenantal diagnosis

Non invasive techniques

Invasive techniques

Non invasive techniques

Those that do not require an incision or surgery

Radiography – when x-rays are used for detection

1. Amniography2. Fetography

Ultrasonography

This is useful in determining

1. Whether the foetus is alive.2. Foetal head size.3. Foetal position.4. Gross structural deformities5. Amniotic fluid volume.

Screening of maternal blood

1. AFP test (Alpha feto-protein)2. Triple test Level of three substances

namely AFP, HCG ( human chorionic gonadoprotein), UE3 (unconjugated estrinol) are tested.

3. Quadruple screen test Inhibin A

Invasive techniquesAmniocentesis

Chorionic Villus sampling

Pre implantation genetic diagnosis

Removal of 2-3 cells at blastocyst stage.

Used to screen those embryos that carry chromosome aneuploidy (high chance of pregnancy loss).

Genetic screening

Definition- Genetic screening is a routine diagnostic procedure employed to detect those are affected by a hereditary disease or carriers of a defective gene.

It applies to population than to individual