. Deficiency of Vitamin A causes night blindness because vitamin A is responsible for synthesis of visual pigment. Vitamin B2 is also called riboflavin. Ariboflavinosis is a deficiency disease due to inadequate intake of riboflavin and characterised by sores on the mouth. Deficiency of vitamin D causes rickets in childhood and osteomalacia in adulthood. Deficiency of vitamin B12 causes pernicious anaemia.