– Thiamine pyrophosphokinase (TPK) produces thiamine pyrophosphate, a cofactor for a number of enzymes, including pyruvate dehydrogenase and 2-ketoglutarate dehydrogenase. Episodic encephalopathy type thiamine metabolism dysfunction (OMIM 614458) due to TPK1 mutations is a recently described rare disorder. The genomic variations in the fetal and maternal TPK1 gene could contribute to the variability of birth weight in normal humans.