Genetic Counselling
What is genetic counselling? Children inherit genes from their parents that determine what colour their hair and eyes are, their body shape, blood group etc. These genes may also contain defects or disorders which may be passed on to the baby What is genetic counselling?
Couples who have a family history of particular diseases and are planning for a baby may ask for genetic counselling to find out if there is a risk of the disease being passed onto their baby Tests can be carried out on unborn babies to see if there are any abnormalities, if there are any detected, then the couple is given the option to terminate the pregnancy Some diseases are caused by faulty genes which can be passed down to generations of the same family
Genetic counselling is offered if… There is a family history of inherited disease, or a previous child has an inherited disease A couple are closely related The mother has two or more miscarriages Ante-natal screening shows an abnormal result Genetic counselling is offered if…
There are 46 chromosomes in every cell in the body except for the sex cells, which have 23 each. At conception they become one cell with 46 chromosomes Together they make a single cell of 46 chromosomes Sperm cell of 23 chromosomes During conception they fuse together Egg cell of 23 chromosomes Basic genetics
Examples of inherited diseases: Cystic fibrosis– thick mucus blocks in the lungs Haemophilia – where the blood fails to clot Thalassaemia – a type of anaemia that is a disorder of the red blood cells Sickle cell anaemia – a disorder affecting the red blood cells PKU (Phenylketonuria) – the brain becomes damaged causing the child to be mentally handicapped Muscular dystrophy – weakens the muscles Examples of inherited diseases:
Inheritance of Sex - gender is determined by sex chromosomes Boys Girls XY = Male Half the sperm cells carry X chromosomes and half of them carry Y chromosomes XX = Female All egg cells carry X chromosomes Inheritance of Sex - gender is determined by sex chromosomes
An egg fertilised by an X sperm will become a girl An egg fertilised by a Y sperm will become a boy X XX – Girl baby X XY – Boy baby X Y The sex of a baby depends on whether the egg is fertilised by an X-carrying sperm or a Y-carrying sperm
Key words… Genetic counselling 23 chromosomes 46 chromosomes Gender Inherit X chromosome Y chromosome XX chromosome XY chromosome Key words…