Haemophilia and Thalassaemia are both examples of Mendelian disorder, but show difference in their inheritance pattern. Explain how.

Explanation

Haemophilia is a sex-chromosomal Mendelian disorder due to recessive gene mutations of sex-chromosome-X. It is also known as bleeder.s disease because the exposed blood does not clot due to absence of plasmathromboplastin or antihaemophilia globulin. The pattern of inheritance is criss-cross inheritance i.e, the male passes the character to the same sex offspring - grandsons through the daughters while the female passes the characters to the grand daughters through the sons. (c) Thalassaemia is an autosomal linked recessively inherited disease, produced due to gene on. It results in reduced synthesis of one of a or B-chain of haemoglobin. The homozygous persons for thalassaemia suffer from severe haemolytic anaemia while the heterozygous persons show the defect in a less severe form or are unaffected. Thalassaemia is a quantitative problem of synthesising too few globulin molecules. They are transmitted to the offspring as per Mendelian principles or laws. In both the male and females, the thalassaemia is controlled by two factors present on the autosomal chromosomes.
While in haemophilia in males the character is controlled by single factor (Hemizygous) present on X-chromosome. The pattern of inheritance of haemophilia and thalassaemia can be traced in a family by pedigree analysis.