The genes in our DNA provide instructions for proteins which are the building blocks of the cells that make up our body. Although we all have variation in our genes, sometimes this can affect how our bodies grow and develop. A variation in gene that causes a health or development condition is called a pathogenic variant or mutation. If a condition only occurs when both copies of the gene are changed, this is called a recessive variant. We’ll have a number of recessive variants which are hidden due to the fact that we have a backup working copy of the gene and therefore enough of the writing product is made.
Recessive conditions mean that you need two bad chromosomes before you get the disease. You’ve got 23 pairs of chromosomes, numbered 1 to 22, and then you’ve got two sex chromosomes. So, recessive conditions are mostly not on the non-sex chromosomes. You need the two bad copies of the same chromosome before you get the disease.
