These are instructions to make thousands of different proteins that the cells in our bodies need to reproduce and remain healthy. Nearly all cells reproduce but retinal cells are one of the exceptions. We inherit one set of genes from each parent. These sets are called Chromosomes and are named 1 to 22. We also inherit a gender determining chromosome from each parent.

Males inherit an X chromosome from their mother and a Y chromosome from their father. Females inherit an X chromosome from both parents. Humans have about 22 000 genes and mutations can occur in any of these genes. There are over 300 genes that have been linked to Inherited Retinal Degeneration and dozens more identified in AMD.

In IRD the mutation can be inherited in different ways. In recessive inheritance parents unknowingly carry a single copy of the mutated gene and may both pass this gene onto their child. In dominant inheritance a single parent, mother or father is affected by the condition and may pass the gene onto their children.

In X linked inheritance the mother is the carrier and may pass the gene onto the sons who will be affected, and their daughters who will again be carriers. This is a very simple explanation, and a genetic counsellor [GC] will be able to analyse your specific family history and give you accurate advice.