<s>[INST] <<SYS>> This is a medical question of type : frequency <</SYS>> How many people are affected by lactate dehydrogenase deficiency ? [/INST] Lactate dehydrogenase deficiency is a rare disorder. In Japan, this condition affects 1 in 1 million individuals; the prevalence of lactate dehydrogenase deficiency in other countries is unknown. </s>