Genetic diseases are conditions that result from changes or mutations in an individual's DNA or genetic material.

These changes can affect the normal functioning of genes and lead to a wide range of health problems, including physical, developmental and cognitive issues. Genetic diseases can be inherited from parents or occur spontaneously due to genetic mutations.¹⁰ It is estimated there are more than 10,000 known rare diseases that exist globally, with 80 percent of these having identified genetic origins.¹¹ Less than 10 percent of rare diseases have an approved treatment option.¹²

Genetic diseases can be caused by a defect in a single gene (also termed monogenic disorders) or by mutations in multiple genes, or by damage to chromosomes resulting in changes to the structure of the chromosome.¹³ There are between 5,000–8,000 monogenic diseases.¹⁴ More than 4,000 monogenic mutations account for at least 80 percent of all rare diseases. These often manifest during childhood and remain largely untreatable, leading to morbidity and sometimes premature death.¹⁵ Sickle cell anemia is an example of a monogenic disorder and Down syndrome is an example of a chromosomal disorder.