 It is still speculated that the isoforms may play a role in specific glycolytic rates in the tissue-specific environments they are in.It has been found in humans that some human tumor cell lines had increased glycolytic productivity and correlated with the increased amount of PFKL.Deficiency in PFK leads to glycogenosis type VII (Tarui's disease), an autosomal recessive disorder characterised by severe nausea, vomiting, muscle cramps and myoglobinuria in response to bursts of intense or vigorous exercise.