Why are colour blindness and thalassemia categorised as Mendelian disorders?

a) Thalassemia:Thalassemia is an inherited autosomal recessive disorder which affects the blood. Haemoglobin synthesized by the body is abnormal and is unable to carry oxygen efficiently. This later leads to the destruction of blood cells and thereby causes anemia. The individuals whose one of the parents is a carrier also becomes a carrier of the disease. If both the parents are carriers of the disease, the individual has 25% chances of getting affected by the disease.
Colour Blindness: Colour blindness is a sex-linked recessive disorder. It is mainly caused by the mutation in the genes present on the X chromosome. In this case, males are more affected compared to females. The female has two X chromosomes. In case one X chromosome is affected by the disease, the other X chromosome can compensate for it. Therefore, the females who are carriers of the disease do not express the disease but can transfer it to the next generation. But in males, there is only one X chromosome. If this chromosome is mutated or affected then the male will surely suffer from colour blindness.
Both thalassemia and colour blindness follow Mendelian inheritance pattern as these disorders are caused by the changes in the single gene which are inherited from parents to offspring. Therefore, they are categorised as Mendelian disorders.