All will know which chromosomes make a boy and which chromosomes make a girl. Most will be able to explain what a genetic counsellor is. Some will understand the importance of genetic counselling and identify at least 3 reasons when genetic counselling maybe needed.

What are genes? Genes are what makes you the person that you are and how much you look like your parents. Every cell in your body has 46 chromosomes, except for the sex chromosomes which are made up of 23 from the sperm and 23 from the egg. Some genes are dominant and can be clearly seen, e.g. The colour of your hair Some genes are recessive genes for example you may have brown eyes but be the carrier of blue and so could pass this on to your children.

How sex chromosomes are passed on x y X X XX XY Girl Boy

What is a congenital abnormality? When a baby is born with a major birth defect. These can be caused by environmental or genetic factors. Genetic abnormalities can be inherited from one or both parents. A genetic counsellor is someone who understands a range of conditions that can be passed on in different genetic ways and can advice couples on how great the risk might be. If a couple feel that they may pass on a condition they can ask their GP for genetic counselling. People may approach a GP to be referred to a genetic counsellor if:

There is a repeated history of miscarriages If there is a blood relationship between the mother and her partner e.g. cousins If a women has previously given birth to a child with a genetic condition e.g. cystic fibrosis or a chromosomal disease e.g. Down’s syndrome. If there is a family history of inherited disorders e.g. Haemophilia If either partner belongs to an ethnic group in which a genetic disorder occur frequently e.g. Sickle cell disease is common mainly in people whose families come from Africa, the Caribbean and eastern Mediterranean. If there is a high rate of some forms of cancer within families If the couple are having problems conceiving.

Down’s syndrome Genetic abnormalities can be created during conception, for example down’s syndrome. Babies with down’s syndrome generally have a broad head with a very round face, with slightly smaller ears and mouth.

Activity Think about your own physical features. Which do you think you inherited from your mother and which from your farther? Do the same for your brothers and sister. How many features do you have the same? How many are different?