(a): Thalassaemia is an autosomal recessive blood disorder. In the given case, both the partners are una ffected carriers for the gene i.e., have heterozygous genotype Tt. Persons homozygous for the autosomal recessive gene of β -thalassaemia suffer from severe haemolytic anaemia. Heterozygous persons are also not normal, but show the defect in a less severe form (thalassaemia minor).