Glucose-6-phosphate dehydrogenase deficiency overview

# Overview
G6PD deficiency was first discovered more than 50 years ago. Prisoner volunteers were given primaquine and some of them developed hemolytic anemia. G6PD deficiency may be classified to into 5 subtypes. It is understood that G6PD deficiency is the result of reduced Glucose-6-phosphate dehydrogenase enzyme levels. G6PD deficiency is an X-linked disorder. Glucose-6-phosphate dehydrogenase enzyme oxidizes glucose-6-phosphate to 6-phosphogluconolactone in pentose phosphate pathway ( HMP shunt). The most common cause of G6PD deficiency is due to genetic disorder. Less common cause of G6PD deficiency include neutrophil dysfunction. G6PD deficiency is affecting 400 million people worldwide. patients of all age groups may develop favism, but more often and severe in children. African, Middle Eastern and South Asian people are affected the most. Men are more commonly affected by G6PD deficiency. Common risk factors in the development of G6PD deficiency include some foods such as fava beans, some medications and infections. The symptoms of G6PD deficiency typically develop after exposure to some foods and medications. Common complications of G6PD deficiency include acute hemolytic anemia and neonatal jaundice.Diagnostic study of choice for G6PD deficiency include quantitative laboratory assay, Beutler fluorescent spot test and DNA testing for mutated genes. The mainstay of treatment for G6PD deficiency is avoidance of the foods such as fava beans and drugs that cause hemolysis. Pharmacologic medical therapy is recommended among patients with chronic hemolysis. Blood transfusion can be considered in acute phase of hemolysis.

# Historical Perspective
G6PD deficiency was first discovered more than 50 years ago. Prisoner volunteers were given primaquine and some of them developed hemolytic anemia.

# Classification
G6PD deficiency may be classified to into 5 subtypes. Class I: Severe deficiency with chronic hemolytic anemia. Class 2: Severe deficiency with intermittent hemolysis. Class III: Moderate deficiency, hemolysis with significant oxidant stress. Class IV: No enzyme deficiency or hemolysis. Class V: Increased enzyme activity.

# Pathophysiology
It is understood that G6PD deficiency is the result of reduced Glucose-6-phosphate dehydrogenase enzyme levels. G6PD deficiency is an X-linked disorder. Glucose-6-phosphate dehydrogenase enzyme oxidizes glucose-6-phosphate to 6-phosphogluconolactone in pentose phosphate pathway ( HMP shunt). Glucose-6-phosphate dehydrogenase enzyme also reduces nicotinamide adenine dinucleotide phosphate (NADP) to NADPH. NADPH is an important cofactor in glutathione metabolism against oxidative injury in RBC. In G6PD deficiency, oxidative stresses can denature hemoglobin and intravascular hemolysis in RBC can happen. The gene G6PD is located in the distal long arm of the X chromosome at the Xq28 locus. G6PD B, is the wild type or normal. On microscopic histopathological analysis, Heinz bodies can be visualized as a result of denatured hemoglobin in peripheral blood smears with supravital staining.

# Causes
The most common cause of G6PD deficiency is due to genetic disorder. Less common cause of G6PD deficiency include neutrophil dysfunction.

# Differentiating Xyz from other Diseases

# Epidemiology and Demographics
G6PD deficiency is affecting 400 million people worldwide. patients of all age groups may develop favism, but more often and severe in children. African, Middle Eastern and South Asian people are affected the most. Men are more commonly affected by G6PD deficiency.

# Risk Factors
Common risk factors in the development of G6PD deficiency include some foods such as fava beans, some medications and infections.

# Screening
G6PD deficiency screening in neonates is done routinely in some regions with high incidence. Screening is done before giving oxidant medication to high risk patients.

# Natural History, Complications and Prognosis
The symptoms of G6PD deficiency typically develop after exposure to some foods and medications. Common complications of G6PD deficiency include acute hemolytic anemia and neonatal jaundice.

# Diagnosis

## Diagnostic study of choice
Diagnostic study of choice for G6PD deficiency include quantitative laboratory assay, Beutler fluorescent spot test and DNA testing for mutated genes.

## History and Symptoms
The majority of patients with G6PD deficiency are asymptomatic. Common symptoms of G6PD include nausea, back pain, headache, chills. Less common symptoms include acute renal failure and shortness of breath.

## Physical Examination
Patients with G6PD deficiency usually appear normal. Physical examination of patients with G6PD deficiency is usually remarkable for Jaundice in hemolysis, Abdominal tenderness in the right upper abdominal quadrant because of hyperbilirubinemia.

## Laboratory Findings
Laboratory findings consistent with the diagnosis of G6PD deficiency include hemoglobinuria, neonatal hyperbilirubinemia, elevated Lactate dehydrogenase in hemolysis

## Electrocardiogram
There are no ECG findings associated with G6PD deficiency.

## X-ray
There are no x-ray findings associated with Glucose-6-phosphate dehydrogenase deficiency.

## CT scan
There are no CT scan findings associated with Glucose-6-phosphate dehydrogenase deficiency.

## MRI
There are no MRI findings associated with Glucose-6-phosphate dehydrogenase deficiency.

## Echocardiography or Ultrasound
There are no echocardiography/ultrasound findings associated with Glucose-6-phosphate dehydrogenase deficiency.

## Other Imaging Findings
There are no other imaging findings associated with Glucose-6-phosphate dehydrogenase deficiency.

## Other Diagnostic Studies
Other diagnostic studies for G6PD deficiency include CBC, Lactate dehydrogenase, Haptoglobin, Urinalysis, Peripheral blood smear.

# Treatment

## Medical Therapy
The mainstay of treatment for G6PD deficiency is avoidance of the foods such as fava beans and drugs that cause hemolysis. Pharmacologic medical therapy is recommended among patients with chronic hemolysis. Blood transfusion can be considered in acute phase of hemolysis.

## Surgery
Surgical intervention is not recommended for the management of G6PD deficiency. Splenectomy may be considered in rare cases.

## Primary Prevention
Effective measures for the primary prevention of G6PD deficency include avoiding triggers.

## Secondary Prevention
Effective measures for the secondary prevention of G6PD deficiency include avoiding triggers.

# Case Studies
Case #1