Down syndrome = trisomy of 21st chromosome Sickle cell anaemia = autosomal recessive disorder, due to the mutation in β-globin gene of haemoglobin, on chromosome 11 Haemophilia = Sex linked recessive disease, caused due to deficiency of clotting factor VII or IX Parkinson Disease = caused by a loss of nerve cells in the part of the brain, that produce neurotransmitter dopamine