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nih rare diseases : 53 the following summary is from orphanet, a european reference portal for information on rare diseases and orphan drugs.orpha number: 713disease definitionphosphoglycerate kinase (pgk) deficiency is a metabolic disorder characterized by variable combinations of nonspherocytic hemolytic anemia, myopathy, and various central nervous system abnormalities.epidemiologyprevalence is unknown but about 30 unrelated affected families have been reported so far.clinical descriptionthe majority of patients present with chronic hemolytic anemia, which may be severe in some cases. myopathy is a common finding and is characterized by exercise-intolerance, muscle weakness, cramping, myalgia and episodes of myoglobinuria. rhabdomyolysis has also been reported in a few patients. intellectual deficit is frequent, and other central nervous system manifestations may be also present including hemiplegic migraines, epilepsy, ataxia and tremor. only a few patients show all three cardinal features of the disorder (hemolytic anemia, central nervous system abnormalities and myopathy), and several cases of pgk deficiency with myopathy in the absence of hemolytic anemia have been reported. only one asymptomatic patient has been described with mild pgk deficiency.etiologypgk deficiency is caused by mutations in the pgk1 gene (xq13.3) and around 20 different disease-causing variants have been identified so far in affected families. pgk is a key enzyme in the glycolytic pathway catalyzing the conversion of 1,3-bisphosphoglycerate into 3-phosphoglycerate and generating atp. pgk is a ubiquitous enzyme expressed in all tissues except the testes.diagnostic methodsdiagnosis is made on the basis of the clinical picture, together with biochemical studies revealing low erythrocyte and muscle pgk enzyme activity (below 23% and 25% of normal respectively), and identification of pgk1 gene mutations by molecular analysis.differential diagnosisthe differential diagnosis should include other causes of hereditary nonspherocytic hemolytic anemia.antenatal diagnosismolecular prenatal diagnosis is feasible for families of an index case.genetic counselingpgk deficiency is inherited as an x-linkedtrait and most of the reported patients were hemizygous males. however, heterozygous females may have a variable degree of hemolytic anemia.management and treatmentin patients with severe chronic anemia, regular blood transfusions are required. splenectomy has been shown to be beneficial in some cases.prognosisthe prognosis is variable, depending on the severity of the anemia and on the presence of the other manifestations.visit the orphanet disease page for more resources.
genetics home reference : 25 phosphoglycerate kinase deficiency is a genetic disorder that affects the bodys ability to break down the simple sugar glucose, which is the primary energy source for most cells. researchers have described two major forms of the condition. the most common form is sometimes called the hemolytic form. it is characterized by a condition known as chronic hemolytic anemia, in which red blood cells are broken down (undergo hemolysis) prematurely. chronic hemolytic anemia can lead to unusually pale skin (pallor), yellowing of the eyes and skin (jaundice), fatigue, shortness of breath, and a rapid heart rate. some people with the hemolytic form also have symptoms related to abnormal brain function, including intellectual disability, seizures, and stroke.
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