Question

thalassemia major why is it occur?
colourblind ness genotype

Answer 1

Thalassemia is an autosomal linked recessive disease which is  transmitted from  parents to their young one when both the parents are unaffected carrier  for the gene,  or  they may be heterozygous.  It is qualitative defect in which ultimately result in reduce rate of synthesis of normal hemoglobin.  

Human hemoglobin has four chain 2 alpha and 2 Beta.  

Two beta chains are identicle.  On this basis their are two types of beta thalassemia .

Beta Minor thalassemia - The individual has only one copy of the beta thalassemia gene and other is affected.

Beta Major thalassemia-when both beta chains are affected and no normal beta chain occurs.

2. Colorblindness genotype - It is sex linked recessive disorder.  The defect is due to mutation in some genes present in X chromosome. So, indivdual with genotype

(XXc) - female carrier

(XcXc)- female affected

(XYc)- male affected