Phosphofructokinase deficiency is a rare muscular metabolic disorder, with an autosomal recessive inheritance pattern. It may affect humans as well as other mammals (especially dogs). It was named after the Japanese physician Seiichiro Tarui (b. 1927), who first observed the condition in 1965. Presentation In humans Human PFK deficiency is categorized into four types: classic, late-onset, infantile and hemolytic. These types are differentiated by age at which symptoms are observed and which symptoms present. Classic form Classic phosphofructokinase deficiency is the most common type of this disorder. This type presents with exercise-induced muscle cramps and weakness (sometimes rhabdomyolysis), myoglobinuria, as well as with haemolytic anaemia causing dark urine a few hours later. Hyperuricemia is common, due to the kidneys' inability to process uric acid following damage resulting from processing myoglobin. Nausea and vomiting following strenuous exercise is another common indicator of classic PFK deficiency. Many patients will also display high levels of bilirubin, which can lead to a jaundiced appearance. Symptoms for this type of PFK deficiency usually appear in early childhood. Late-onset form Late-onset PFK deficiency, as the name suggests, is a form of the disease that presents later in life. Common symptoms associated with late-onset phosphofructokinase deficiency are myopathy, weakness and fatigue. Many of the more severe symptoms found in the classic type of this disease are absent in the late-onset form. Infantile form Phosphofructokinase deficiency also presents in a rare infantile form. Infants with this deficiency often display floppy infant syndrome (hypotonia), arthrogryposis, encephalopathy and cardiomyopathy. The disorder can also manifest itself in the central nervous system, usually in the form of seizures. PFK deficient infants also often have some type of respiratory issue. Survival rate for the infantile form of PFK deficiency is low, and the cause of death is often due to respiratory failure. Hemolytic form The defining characteristic of this form of the disorder is hemolytic anemia, in which red blood cells break down prematurely. Muscle weakness and pain are not as common in patients with hemolytic PFK deficiency. In dogs Presentation of the canine form of the disease is similar to that of the human form. Most notably, PFK deficient dogs have mild, but persistent, anemia with hemolytic episodes, exercise intolerance, hemoglobinuria, and pale or jaundiced mucous membranes. Muscle weakness and cramping are not uncommon symptoms, but they are not as common as they are in human PFKM deficiency. Risk factors In humans