Sickle cell anaemia is an autosomal disorder. It is the most common genetical disorder appear in Africans. The disease is due to the substitution of sixth codon in gene coding for the b-chain of Haemoglobin. Due to this, sixth amino acid in b-chain of Haemoglobin Glutamic acid is replaced by valine. The main symptom of this disorder is decrease of oxygen uptake.
So, the correct option is ‘VI’.