Pernicious anaemia is due to the deficiency of vitamin ${\mathrm{B}}_{12}$. The deficiency of vitamin ${\mathrm{B}}_1$ causes Beri beri . The deficiency of vitamin ${\mathrm{B}}_6$ causes Convulsions. The deficiency of vitamin ${\mathrm{B}}_2$ causes cheilosis (fissuring at corners of mouth and lips), digestive disorders and burning sensation of the skin.