Autosomal Recessive diseases comprise almost 1/3 of one-gene diseases. To be able to encounter these diseases, a pair of gene situated at the same locus should both change functuonally. Patients who have a change at just one of the pair of gene are called  disease carrier. Autosomal recessive diseases do not show themselves in every generation. And the family tree has a horizontal pattern. Parents are healthy in general and the disease is observed at same generation according to the index. Marriage between relatives, having the same ancestors increases the risk of conveying the mutant gene that causes the frequency of autosomal recessive patients.

The disease do not discriminate the sex and advances at the same level. Disease carrier couples have the risk of 25%. At recessive diseases the risk of being disease carrier for the children is 50% . However the risk of not conveying the mutant gene is 25%.  The risk of seeing the disease at children is 0% if a disease carrying person marry to who has no a mutant gene. If a patient marry to who has no a mutant gene, then all the children will be disease carriers but healthy. If a patient marry to who is disease carrier, then the risk of see in the disease at children for every pregnancy is 50%, and the risk of being a disease carrier is also 50%.

Beta thalassaemia is one of he disases seeing mostly in Turkey as those all Mediterannean countries. Although the frequency of carrier changes from the region to region, it is nearly 2-3%. In our country marriages between relatives are frequently seen, so we have many affected pregnancies. This situation results in an obligatory ending at pregnancies. Population scanning show that we have already have many thalassaemia mutations.