Editing Pyruvate kinase deficiency (section)

==Cause==
Pyruvate kinase deficiency is due to a mutation in the [[PKLR]] gene. There are four [[pyruvate kinase]] [[Isozyme|isoenzymes]], two of which are encoded by the PKLR gene (isoenzymes L and R, which are used in the liver and [[Red blood cell|erythrocytes]], respectively). Mutations in the PKLR gene therefore cause a deficiency in the pyruvate kinase enzyme.<ref name="hom">{{Cite web|url=http://ghr.nlm.nih.gov/condition/pyruvate-kinase-deficiency|title=Pyruvate kinase deficiency|date=2015-11-09|website=Genetics Home Reference|access-date=2015-11-11}}</ref><ref name=":4" />

180 different mutations have been found on the gene coding for the L and R isoenzymes, 124 of which are single-nucleotide [[missense mutation]]s.<ref name=":5">{{Cite journal|last1=Christensen|first1=Robert D.|last2=Yaish|first2=Hassan M.|last3=Johnson|first3=Charlotte B.|last4=Bianchi|first4=Paola|last5=Zanella|first5=Alberto|title=Six Children with Pyruvate Kinase Deficiency from One Small Town: Molecular Characterization of the PK-LR Gene|journal=The Journal of Pediatrics|volume=159|issue=4|pages=695–697|doi=10.1016/j.jpeds.2011.05.043|pmid=21784452|date=October 2011}}</ref> Pyruvate kinase deficiency is most commonly an [[Dominance (genetics)|autosomal recessive trait]].<ref name=":6" /> Although it is mostly [[Zygosity|homozygotes]] that demonstrate symptoms of the disorder,<ref name=":3" /> [[Compound heterozygosity|compound heterozygotes]] can also show clinical signs.<ref name=":5" />