Glyukozo-6-fosfatdegidrogenaza (G6FD) is represented by the enzyme which is contained everywhere in all cells. However its insufficiency has potentially pathological consequences only in erythrocytes. The deficiency of G6FD, or insufficiency of G6FD (also G6FD enzimopeniya), is the most widespread erythrocyte fermentopatiya at people. It was counted that at least 500 million people in the world have a gene mutation which results in defect of activity of G6FD enzyme. The deficiency of G6FD is widespread worldwide and especially often meets in Africa, on the Middle East, in Asia and the Mediterranean. Variations of G6FD enzyme have different levels of activity, and it involves various manifestations at the clinical level:
Options of class I meet extremely seldom, are provided by the expressed insufficiency of enzyme (10–20% of normal activity) and chronic hemolitic anemia;
Class II options, such as Mediterranean G6FD type, represent even more serious deficiency (<10%) and high risk of episodes of acute hemolitic anemia;
Class III options, such as Seattle in populations of the African origin with deficiency from heavy to moderated (10–60%) and rare episodes of acute hemolitic anemia.
Provocative factors include consumption of some bean, drug intake with the intracellular oxidizing action, influence of substances with the intracellular oxidizing effect, bacterial and viral infections (moderate severity). The listed provocative factors, at their visible heterogeneity, have the systemic oxidizing effect on erythrocytes. Emergence and intensity of hemolitic crisis depends on a dose of a provocative factor therefore not necessarily occurs after any influence of one of the listed factors. At most of people insufficiency of G6FD proceeds asymptomatically throughout all life: in other words, at deficiency of G6FD absolutely normal quality and life expectancy remains, and it is possible not to suspect about existence of this fermentopatiya if in the past there were no obvious clinical manifestations. Spontaneous clinical manifestations take place only in the neonatal period; subsequently acute hemolitic crises can be provoked by consumption bean, infections or intake of some drugs.
Diagnostics of deficiency of G6FD is carried out by qualitative (screening) and quantitative tests, at the same time blood samples take away in a test tube with anticoagulant. Screening tests are usually used for identification of persons with deficiency of G6FD according to programs of screening of newborns or in risk groups where the frequency of occurrence of enzymatic defect is high. In case of positive screening test the diagnosis has to be confirmed with the quantitative test which measures activity of G6FD.
There are no data indicating special susceptibility to an infection of SARS-CoV-2 of people with deficiency of G6FD today. At the moment there is no specific treatment of this disease, and patients with an infection of SARS-CoV-2 receive therapy by several existing drugs which are already used for treatment of other viral infections. For persons with deficiency of G6FD the infection of SARS-CoV-2 represents an accessory factor of risk therefore chloroquine and hydroxychloroquine which were used for treatment of COVID-19 should not be applied at patients with heavy deficiency of G6FD as can become the reason of hemolitic crisis at the patient. In case of already begun treatment by chloroquine or hydroxychloroquine and impossibility to receive quantification of enzyme in appropriate terms, at emergence 3-5 days later from the beginning of administration of drug of sharp decrease in level of hemoglobin at least on 1.5-2 g/dl and dark urine it is necessary to consider a possibility of deficiency of G6FD and to interrupt treatment. It should be noted that recently in connection with accumulation of results of researches which show inefficiency and insecurity of use of chloroquine and hydroxychloroquine at treatment of COVID-19 use of these drugs by a number of authoritative associations is not recommended in general at this infection.
Concerning all other drugs which can be used for treatment of COVID-19 there are corresponding methodical recommendations containing concrete therapeutic indications within which it is possible to provide controlled and their safe use in the current emergency situation, giving clinical physicians useful links for a rukovodstvovaniye them at appointment and definition for the patient of a ratio of advantage and risk of each used medicine.