What are recessive diseases?

Recessive diseases are those genetic diseases in which both copies of the same gene are damaged. That is, a person who only has one mutated copy will be a “carrier” of the disease, but will not develop the disease and, therefore, will not have any symptoms. However, a person who carries two damaged copies will develop the symptoms of the disease. Therefore, many of these diseases can be transmitted from parents to children without them having any suspicion of it. If it coincides that both the mother and the father are carriers of the same disease, approximately 25% of their children will suffer from the disease.

Recessive diseases are known as rare diseases, since they are rare. Although this category assumes that the disease affects 1 in 2,000 people, there are more than 7,000 rare diseases, so the combined incidence of all of them is high.

Enfermedades autosómicas recesivas

Autosomal recessive diseases

For the majority of genes, we inherit two copies, one from the father and one from the mother. These types of diseases only manifest if both copies are affected (25% chance). If only one parent is a carrier, the child will have a chance of being a healthy carrier.

X chromosome-linked diseases

Women have two X chromosomes, while men have one. Some disease variants are found on this chromosome.

If a woman is a carrier of a disease variant on the X chromosome, each of her children has a 50% chance of inheriting this (sons will be affected and daughters will be carriers).

If a man is affected by an X-linked disease, all his daughters will be carriers since they inherit his X chromosome with the variant, whereas the sons will not be at risk since they have inherited the Y chromosome from the father.

Which diseases does
HERES Carrier Screening detect?

HERES Carrier Screening evaluates the genes responsible for more than 300 recessive and X-linked inherited diseases, such as:

Cystic fibrosis

Fragile X syndrome

Sickle-cell anaemia

Sickle-cell anaemia

Tay Sachs disease


Canavan disease

Bloom’s syndrome

Wilson’s disease