Which of the following is not a genetic disease?

Haemophilia is a genetic disease in which the blood does not clot. It is caused due to an error of DNA and the error is present on X chromosome but it is expressed in males only. Sickle cell anaemia is a genetic disorder in which the haemoglobin is defective and not efficient in O2 transport. This defective haemoglobin distorts the shape of RBC’s in which it is stored and they look sickle-shaped. Hence, the name “sickle cell” is derived. Being sickle shaped, it is difficult for the RBC’s to move freely in the blood vessels and so supply of oxygen to different organs and cells become slow and hence, respiration and release of energy becomes low, thereby making us feel lethargic. This disease is referred to as “anaemia”. Night blindness is a disease in which a person cannot see clearly in dim light due to defect in rod cells of retina. All these are genetic disorders. But, influenza is caused due to virus which is an external agent and hence, it is not a genetic disease. Thus, (1) (2) and (3) options are genetic diseases while (4) is not a genetic disorder.